The classic sf short story "The Midas Plague" by Fred Pohl. The world is being drowned by the output of automated factories, and it never occurs to anyone in the entire world to turn them off or run them at a slower pace or even just destroy the output directly. Instead, people are required to use up the output, e.g., play lots of tennis to wear out the rackets and balls.
The whole shtick of the Amelia Bedelia is that the titular maid takes everything she hears literally and so frequently screws up instructions. After the first few times, her employers should've learned to phrase things literally for her like "close the drapes" instead of "draw the drapes" or "prepare a bridal party" instead of a "bridal shower", but they never do. What makes it weird is that it was stated at the end of the first book that her employers learned to do that, and then they completely forget to do so for the rest of the series.
Angels & Demons has a huge gaping hole that not a single character sees. Great care is given to say how undetectable the antimatter containment is. The protagonists even go so far as to wipe out power to entire city blocks so that they can look for the containment device without any background noise. Yet no one thinks to look for the camera pointed at the containment device that is actively broadcasting. Since they are receiving video, there is a signal. Since there is a signal, it can be triangulated.
Granted, the movie has fixed a lot of the Idiot Plot, and has Langdon openly lampshade a lot of the stuff that only happens because of stupidity (e.g. when going to find the water victim, Robert yells at the cops for discussing what to do instead of rushing to the scene and helping him). Mind you, not that it saves the film from occasionally veering into idiot plot territory.
As the Animorphs series kept getting longer, the premise of the kids having to hide the truth from everybody kept getting less believable.
#31 The Conspiracy: The whole book is about Jake secretly trying to get his brother freed and keep his father from becoming infested or killed. The fourty-ninth book shows that revealing the truth to their families is as simple as just morphing in front of them so they can't deny the craziness of what they're being told. Yet Jake doesn't consider that once in the whole book, so that the series can keep going. As a result, his brother stays infested and his parents are infested later come said 49th book.
#14 The Unknown: The team encounters a military battalion that is demonstrated not to be infested by Yeerks, proven by that they uncover a plot by the Yeerks to infest this group. However, the kids completely ignore the potential of revealing the truth to this trustworthy group, and foil the one infestation attempt with no guarantee that the battalion won't be attacked again.
#21 The Threat: The entire conflict about David being forced to live in a barn and thus feeling resented would have been solved if he had been sent to live with the Chee in their comfy house instead, just like what is done with Marco's dad twenty-four books later.
#50 The Ultimate: Cassie lets Tom get away with the morph cube (thus ensuring the Yeerks can morph, and the Animorphs can't get any more new members), when she could have intervened just enough to save his life, which not only would have kept them the cube, but also allowed Jake to de-infest his brother. This act crosses over into Lethally Stupid territory in the last book, as it makes Cassie indirectly responsible for Rachel's death.
Left Behind is full of this, especially in the early books.
A nuclear assault on Israel ends in no casualties. You'd think that evangelists of every religion would be trying to link it to their own, there would likely be a large amount of conversions, and hard-core atheists would be trying to desperately come up with explanations as to how it could be a natural occurrence. Instead, everyone seems to just go about their business as if it hadn't happened.
Related to this, Russia launches a nuclear strike on Israel, despite Israel being known to have an essentially indestructible second strike capability with most of their missiles believed to be aimed at Russia. They also apparently think it's necessary to launch their ENTIRE arsenal of over a thousand nukes at Israel, leaving their nuclear deterrent completely depleted despite the fact that Israel is small enough to easily be annihilated by one or two large strategic nukes. This strike apparently triggers a response from neither Israel itself nor from any other country despite the fact that the Russians are clearly insane and no longer have any nuclear deterrent. Oh, and the reason the Russians launched this strike in the first place? Israel wouldn't give them the secret to their new miracle-gro formula! Also Etheopia joined this attack for no apparent reason.
Every child in the world disappears in the rapture, but some adults do too. All of these adults are "real true Christians." Somehow, this exceedingly obvious pattern is not noted.
Carpathia's Technobabble explanation for said disappearances is apparently accepted readily. Apparently all the scientists who would rebuke it for its inaccuracies forgot everything they knew.
Most of Carpathia's machinations require this to work. Asking countries to destroy most of their nuclear weapons and give the remainder to him? And they fall for it?
Honorable mention should also go to the Global Community Faith. Carpathia gets some religious leaders together, they hold a press conference announcing that as of now, all religions are now united into a new, only vaguely defined, faith. And everyone except newly converted premillennial dispensationalist Christians and the Jews are happy to go along with it.
And then there's Carpathia's speech to the UN, which consists of a brief history of the UN, a list of the countries in the UN and the people representing them, and a few feel-good phrases that don't actually mean anything. All repeated in nine different languages. The fact that every person listening receives this as being the best speech they've ever heard implies that everybody on earth except Carpathia really is a massive idiot. (The book actually explains this as a form of mind control; anyone but Carpathia giving the speech probably wouldn't have been laughed off the stage, but only because diplomats have a lot of practice in being polite.)
Isn't Carpathia supposed to be the Antichrist? Maybe projecting a Stupidity Field is actually one of his powers.
Another case was pointed out in the Slacktivist blog, with Buck learning about the Great Conspiracy and Carpathia's role in it because a friend of his committed a very suspicious suicide; this happened within a day of the Rapture, meaning that simply knocking him out, hiding him in the car boot and burying him in an unmarked grave somewhere off the beaten track would have simply added his name to a very, very long list of unsolved disappearances. When the population of the planet has decreased by millions or billions overnight, why bother with a staged suicide?
Carpathia's entire plan is one of the things that meant either God is controlling everything that happens directly and thus there is no actual conflict in the story, or Carpathia deserved his defeat due to his sheer stupidity. His entire plan can easily be summed up as following a prophecy that he knows is guaranteed to lead to his defeat to the letter (including doing things like building a temple in Israel solely so it can be there for him to destroy later) and then attempting to break out of it at the very last possible second.
Mentioned in one of Isaac Asimov's Black Widowers stories: One character mentions he's having trouble writing his story without it turning into an Idiot Plot, and was trying to find a way to prevent characters from asking the obvious question that would resolve the mystery. Their guest then causes another Idiot Plot in much the same way.
It is so full of potentially lethal errors in judgement by both the protagonists and antagonists that a strong argument could be made for the series consisting almost exclusively of Idiot Plot, particularly in the latter books.
The greater majority of the protagonists problems are caused by their own lapses in judgement and failure to communicate, to the point that it would take hours to list them all. They refuse to work together, they run off by themselves in secret (repeatedly), they almost never ask for help, and even those that *should* trust one another withhold secrets for no good reason. Not only does it allow the antagonists to win many of their conflicts, it also prevents the heroes from gaining the strength they need to oppose the Dark One. Fortunately, the antagonists also have this failing.
The White Tower rebellion plotline has turned into this. One side of the conflict has rediscovered several lost spells, has a large army led by a famous general, and has surrounded the White Tower, preventing most movement. The other side, inside the tower, are at each other's throats, constantly in-fighting, and are vastly outnumbered due to their leader being Too Dumb to Live. Not to mention the fact that the Chosen One will never make a treaty with the Tower because their leader ordered his kidnapping, and beating. Granted, the Black Ajah is doing its best to foster these problems, but one would think that the Tower's ruling body would, at some point, notice that they are in a ridiculously weak position, their leader is a fool, and remove her from power. And all this is going on with the final battle over the fate of the world just around the corner...
The whole thing ends with the White Tower raising Egwene and only because Elaida was captured by the Seanchan followed by Egwene calling the entire tower Aes Sedai disgraces because only Sylviana had the balls to do what was right.
The title character would have never sunk his fangs in Mina's neck if the heroes had remembered anything they'd learned about vampires during their ordeal with Lucy. Especially since Mina was displaying all the symptoms of being a vampire victim that Lucy displayed earlier... Exacerbated by the fact that Mina was with her when Lucy was first attacked and started displaying those symptoms. And they had Van Helsing with them the whole time.
The way Lucy's mom undermines every effort to save her. Really looks like she's doing it on purpose.
But then again, Van Helsing is very stingy with his information. Okay, don't come into it saying "Obviously the count is a centuries old corpse out to murder everyone in London and is in the process of turning Lucy into his bride," but especially after you've gained the group's trust, you should really take the time to explain what's happening. He barely gives Seward any clue that things like garlic and crucifixes are useful, but then sinks into depression when people that he didn't even talk to don't know that. After Lucy dies, he has the opportunity to behead her with Seward, who completely believes him, but suddenly decides that the rest of the group has to be convinced first, despite the fact that they'd never even need to know it had happened in the first place.
Also for an all-powerful vampire, you'd think Dracula would have had more common sense. Such as taking Lucy with him after fully vamping her rather than leaving her behind. Not only did he give the heroes an example of what a vampire was like and what they could do - he practically led the heroes straight to him. What's the point of making undead women if you're not going to use 'em?
To attack Mina, Dracula had to break into the building where all of his enemies are sleeping multiple times without detection. While he does make an attempt to destroy their notes, he completely ignores this perfect opportunity to kill them all at once.
Another vampire example, the entire plot of Barb Hendee's Hunting Memories depends on the heroine's (using that term loosely, since she is a mass murderess) stubborn refusal to even consider the possibility that the villain (arguably, he is just defending himself) hasn't completely given up after the end of the first novel, and won't ever try again, even though he was clearly a fanatic. One of her companions, who knew the villain much better, didn't think he'd just give up.
There's this empire in Africa which conquers everything it can grab (talking about whole continents here), enslaves pretty much everyone, has an extremely supremacist ideology, plus supreme technology, acts like it's independent even while being a British colony, but no one - whether Nazis, Communists or good democrats - decides to do anything to stop them.
The premise is that the Draka are a sort of Evil Twin society to the United States. Historically, no major nation decided to stop the US from becoming powerful from 1812 up to World War II. The catch, and this is where the idiocy comes in, is that the US wasn't deliberately expanding into the spheres of interest of countries powerful enough to stop it, except for a few minor border clashes with the British Empire over a river valley here and there. Whereas the Draka do, especially during their alternate version of World War I.
There's more idiocy to that, because during much of their power grab the Draka are still a British Dominion, and not once does the British Empire even attempt to slap them down despite repeated brutal, hostile and illegal actions.
There's an attempt at justifying it in the story, arguing that the British Empire was so traumatized by the loss of Canada in the War of 1812 that it didn't feel powerful enough to impose its will on the colonies. (In Real Life, the British Empire at the height of its power barely won a war against two insignificant republics in a small part of what's now South Africa - it's an open question how it would have fared against a heavily militarized, technologically advanced power controlling a large part of a continent.) The Draka are also very careful not to tread on Britain's toes until they are powerful enough to get away with it.
Completely left unaddressed is the presence of France in the presumptive Drakan empire. The French presence in west Africa was well-established by the time the Draka get there, and France is almost as powerful as Britain during the 19th century (they have the second-largest navy in the world, and the largest modern army, during this period). Why there wasn't a more generalized conflict between Britain and France over a rogue British colony impinging upon the French sphere of influence (or why the French didn't just send the Draka home with their asses firmly kicked) is an exercise for the reader.
This site does a good job of pointing out most (though not all) of the flaws in logic, not to mention the blatantly illegal things done by the Draka while they are still firmly under British rule (illegal under 19th century British rule that is).
Pretty much everything that P. G. Wodehouse ever wrote, but the man was so incredibly good at it, you barely notice. Plus, let's face it; when you're dealing with characters like Bertie Wooster, what else do you expect?
Being There, both novel and film, is a satire that uses an Idiot Plot to help make its point. The whole story hinges on how people who believe themselves to be sensible and intelligent nevertheless jump to their own, desired conclusions time after time in their dealings with Chance the Gardener, never asking the questions most people would be tempted to ask based on what he says. This is partially because he appears to be a sensible, intelligent person himself, but is in fact an imbecile who doesn't understand what's going on and thus isn't able to correct others.
The entire Dutch novel Descartes' Dochter (Descartes' Daughter), which revolves around the discovery of a lost manuscript of Descartes. When the main character Henriette returns home to her girlfriend Maartje in a coat covered in blood, Maartje gives up trying to find out what happened after a half-assed attempt at questioning, and the two proceed to make love. Later in the story, when Henriette murders her own mother, Maartje does not go to the police, does not get the hell away from Henriette, but e-mails the French professor she has been corresponding with about it. Who responds with only some vague philosophical stuff about "the gift". Later on, Maartje converses with a German professor about a lost manuscript of Kant that has turned up. When the German professor hears that Maartje has also been corresponding about it with that French guy (the actual French philosopher Jean Luc Marion), she exclaims: "Oh no! A Catholic!" and takes a train to Holland straight away, where she is immediately murdered by Henriette. Later, Henriette lures Maartje into the toilet on a train and then kills her. Serves her right for being Too Dumb to Live.
They accidentally drink the Love Potion meant for Isolde and Mark. They don't even consider asking king Mark permission to marry or anything. Granted, an oath is a pretty big thing, but so is permanent magic, and it's not like Mark cared that much.
Kathy Reichs' Temperance "Bones" Brennan novels depend strongly on this trope for about half the plot, and nearly every major climax. This is particularly true when the climax involves the main character, who seems to pick up the Idiot Ball on nearly every possible occasion. Particularly when it would get her into yet another life-threatening situation by going somewhere alone and unarmed, no matter how many people are telling her not to, which she does in the majority of the novels. When other characters do this, it's either because they've picked up her Idiot Ball, or because they're Too Obsessed/Absent-Minded/Naive/Fluff-headed To Live.
Digital Fortress is a particularly bad example. Even if you ignore the fact that the plot relies on every single person in the world not knowing the very basics of cryptography, it still doesn't make much sense.
Magic 2.0: Played with in the second book, Spell Or High Water. Someone is attempting to kill Brit the Younger by dropping statues on her and magically shooting arrows at her. That's stupid just to start with, since like all sorceresses Brit is completely immune to physical damage, but the really stupid part is that Brit the Younger is part of a Stable Time Loop, and her older self is one of the leaders of the city. So there are really only three ways the assassination plot can go: Either it's impossible to break the loop (in which case the plot is doomed to failure), it is possible to break the loop but the paradox destroys the entire city, or the assassination is successful and there is no paradox but then the conspirators get caught anyway because there just aren't that many suspects. It's pointed out repeatedly that this plan is moronic; in fact, the heroes end up dismissing most of their suspects because none of them are stupid enough to do it. It's only when they are reminded that smart people can do stupid things sometimes that they finally put the pieces together: President Ida gave her servant limited magical powers because she's in love with him. He then used these powers to try to kill Brit the Younger (which, if successful, would make Ida the only remaining authority in the city) because he's an idiot.
"Dismissed with Prejudice" by J. A. Jance. Let's see, the back cover tells us about a Japanese businessman found dead of an apparent suicide. But an error in the ancient ritual pointed to... murder! The actual problem, according to a Japanese-American investigator, is that the scene is "totally wrong" for the ritual suicide. But we have a Caucasian medical examiner persist with his theory of suicide. A couple days later, we discovered that the victim was indeed murdered — bludgeoned over the head. "We couldn't see it until after we moved the body."
House Rules is often criticized for this. Many reviewers note that the entire premise of House Rules depends on barely anyone asking Jacob whether he committed the murder or not. His mother and lawyer immediately organise an insanity defence instead. This is particularly glaring because one of the traits of Jacob's Asperger's is that he's terrible at lying. The plot would also be over in fifty pages if Theo didn't sit through his brother's arrest, jail time and trial, and all the strain this causes on his family, without telling anyone that he broke into Jess's house on the day of the "murder" and saw her fall down and hit her head. All right, maybe he's frightened of being charged with causing her accidental death, but when he finally owns up that doesn't seem to have occurred to him.
Classic of Russian SF Ivan Efremov'sAndromeda Nebula is a perfect example of Idiot Plot. Starship crew was trapped on the planet of Iron Star because watchkeepers just didn't want to wake their commander (despite they knew that he wanted to drive the ship in this area himself). On the planet they've found another Earthian starship, abandoned because its crew was terminated by local aggressive fauna. The last member of dying crew left a record, which contained nothing helpful - except the advice not to leave the ship, never (considering the fact that this record could be picked only by one who had already left his ship, advice is more than senseless). And it is just the beginning...
Blacklisted by Gena Showalter has a mild version of this. The Alien Investigation and Removal agency hunts down and arrests high schooler Camille and her crush Erik. First of all, why would she follow him, when he apparently seems to be a drug dealer? Even if you hand wave that to blind love, why would AIR not just ask her if she was with him or not? As seen in the companion book, their policy is to keep civilians out of their business. Instead they assume that she's a drug dealer too and shoot and arrest her.
"The Deadly Mission of Phineas Snodgrass". So a man travels back in time and pretty much literally Gives Radio to the Romans. Okay, that's not the Idiot Plot. The society which this man creates develops the scientific method much more quickly than it arose in Real Life, and as a result is fully-modernized by around the sixth century and is practically Raygun Gothic by the Middle Ages. And the writer expects us to believe that in all that time no one in that scientifically-minded society ever noticed the massive overpopulation problem that was arising or took any steps to mitigate or prevent it? You'd think that, with no religious restrictions against such things, that reliable birth control would be invented as soon as their society advanced enough to discover modern medicine and learn what causes reproduction. It pretty much stretches Willing Suspension of Disbelief that the only way this advanced society could think to save themselves from an overpopulation-induced catastrophe was to send another person back in time to prevent their society from being founded. What are they, suicidal? Also, the Romans had a cultural lack of compunction about Offing the Offspring, as well as already understanding several modern birth control methods.
A debatable one in Dirty Little Secrets by C.J. Omololu. Lucy is the daughter of a compulsive hoarder who comes home one day to find her mother dead under a stack of junk. She starts to dial 911, but panics and doesn't dial. She was afraid that her friends might find out about how messy her house was and pity her. In the end, she burns the house down. She only calls her brother once, and gives up. Instead, she tries to clean up the house so it at least looks presentable. If she had just called 911 after cleaning up the house somewhat, she probably could have been better off. If she had even called her brother a second time, she probably could have avoided having to burn the house down.
Harry Potter and the Philosopher's Stone: You have to question Dumbledore's wisdom in telling all the students at the start of the book not to try to get past a certain door. A certain door that can be unlocked with a simple charm and has an enormous, extremely dangerous multi-headed dog behind it, ready to maim anyone, adventurous student or not, who gets near. Not to mention the basic concept of putting something that you know the Big Bad is trying to get to in a school is just asking for trouble.
The traps are also suspiciously weak. They provide a challenge to first year students and require the full mix of the trio's strengths, but any older student or adult wizard could bypass them easily as Quirrell is implied to have done - well, aside from the logic puzzle, which at least had an explanation that wizards mostly suck at logic. But still, that's a rather broad generalisation to justify use as a device to protect such a valuable item. Of course, the Mirror of Erised would foil any attempt at taking the Stone anyway (it can't be removed by anyone who wants to use the Stone), so the traps are really meant to slow the thief down. Which they do.
Harry Potter and the Goblet of Fire: It is idiotic for Fake!Moody to have gone through all the trouble to turn the trophy into a Portkey and send Harry to Little Hangleton during the most conspicuous moment in the Hogwarts school year. A Portkey can be made to look like anything, so it would have made sense for Moody to have invited Harry to his office and made him touch a book or something there, with no witnesses. Supposedly the reason for the convolution is that you can't apparate to and from Hogwarts and the Portkey was an exception, but Hogwarts is not known for being safe - a much simpler and efficient way would have been to take his body and dump it in the Forbidden Forrest, where there are dozens of creatures that could've potentially killed him, or throw him to the Whomping Willow, or even make it look like a broom flying accident, and as a bonus that would actually be less suspicious than putting him in the Tri-Wizard Tournament as the fourth competitor and then try to guide him to win the tournament.
For that matter, everyone thinks Harry volunteered for the tournament. In the same book that introduces the Veritaserum, a substance the prevent people from lying. Couldn't they just give him a dose of it in public and ask him if he did volunteer? Instant name-clearing! Granted, Word of God says it isn't admissible in court since a wizard could protect himself against it, but a 14-year-old probably couldn't and it would probably be good enough for public opinion.
Voldemort tries to kill Harry (with Avada Kedavra, the same spell that backfired horribly the first time) in front of his followers, instead of just letting him bleed out or having Pettigrew strangle him to death, then present the corpse to the Death Eaters. Also, he leaves an easily usable Portkey around while giving Harry the wand to get it, instead of just destorying the Portkey after capturing Harry.
Harry Potter and the Half-Blood Prince: The minor side-plot that gives name to the sixth book rests entirely upon it. It's traditional in (muggle) British schools for teachers to keep their favorite moth-eaten, scrawled on textbooks in the book cupboard with the books normally passed out to the children who forget their books, resulting in plenty of amusing anecdotes about the fights kids get into to avoid being the one stuck with that torn copy despite the fact it's often the most useful book to end up with. Whether Wizarding schoolteachers do it or not, Rowling clearly played on this, right down to Ron and Harry fighting over who got stuck with it, and yet somehow they were both completely incapable of ever wondering if it belonged to either the current or past Potions Masters. Not even Hermione was capable of wondering what really should have been an obvious first suspicion for a British kid in a British school system to have. Of course, if they had jumped to the logical suspicion, the sixth book reveal would have happened at the start instead of the end—although that would not have changed the overall plot of the book in any significant way.
The entire seven books would have come crashing down if the Potters had just served as their own Secret Keepers as Bill did for himself and Fleur, or Arthur for Aunt Muriel's. Or for that matter, let Dumbledore be the Secret Keeper, as he had already offered.
Galápagos doesn't just abuse this trope, but positively runs on it in its entirety. The book is basically nothing but the characters acting like utter morons and the author dropping a Contrived Coincidence in their way all the time.
With House of Leaves, the Navidsons could just move out. It's a house. A scary, scary house, but a mostly nonmovinghouse all the same. Johnny could, you know, stop reading The Navidson Record. Pelafina could... stay insane? Okay, so not everyone has a simple solution.
Pretty much any novel by Michael Crichton is a combination of this and Murphy's Law run amok. It's usually not so much that every character is an idiot as that the ones who aren't idiots don't find out what the ones who are idiots have done until it's too late for them to fix it.
Artemis Fowl: The entire berserker threat would never have occurred if they had simply shot the future Opal BEFORE they put her in the tube and she became all powerful.
Luke tells Leia that force-sensitive babies are very susceptible to being warped by the dark side (despite the fact that such a thing has never been mentioned before or since, meaning Luke had his facts way wrong). Princess Leia decides that the best thing to do protect her new children is therefore to put them on a secret planet that not even she knows about, for two years alone with her best friend, completely undefended should the Imperials somehow discover the location (which they inevitably do). This whole plot would have been avoided had Leia realized she was being a little too paranoid and conceded that the kids would be just fine on the well-defended Coruscant growing up with them.
The spirit of the Sith lord Exar Kun is on Yavin IV turning the students at the Jedi Academy to the dark side. When Luke first hears about these strange happenings, one of the students gets killed, and another student openly attacks him and tells him that he's not as good as his other teacher, Luke decides the best course of action is to investigate... some other day. This gives plenty of time for Exar Kun to warp Luke's most promising student into getting a weapon of mass destruction and waging a star-exploding war on the Imperial remnant.
With said corrupted student, Exar Kun manages to get him to channel the dark side and put Luke into a coma where his spirit is sort of a force ghost. Later, the Sith Lord decides he needs to destroy Luke's body so that he could never return (apparently he never thought of that when he had the student put Luke into a coma), so he tries all sorts of over the top plans like making one of the students sleepwalk and lift Luke up with the force so he could be defenestrated and fall to his death in the jungle. Or summon a bunch of dark sided beasts to tear apart his body. It'd be much easier for him if he just got a student to sleepwalk, pick up Luke's lightsaber conveniently placed right next to him, then stab him where he lies. Also despite these constant attacks, the students at the academy are content with letting R2-D2 guard Luke and just hoping that someone more competent comes in time to save the day. Given how over-the-top Kun is, he probably wouldn't have wanted to do something that simple.
Terpfen, a Mon Calamari, is forced to act against his will to sabotage the New Republic because the Empire implanted him with a mind control device. Among other things, he sabotages Admiral Ackbar's B-Wing so it crashes into a populated area (causing him to resign his post), helps poison Mon Mothma, and reveals that baby Anakin Solo is hidden on the planet Anoth. When he becomes free of the mind control in the third book, Terpfen could just walk down the hall and tell any of the New Republic leaders what he did so that they can reinstate Ackbar, start creating an antidote for Mon Mothma, and send a whole fleet to intercept the Empire en route to capturing Anakin. But that doesn't occur to him.
It gets worse. Instead, he decides to go down to the hangar, assault the ground crew and hijack a ship, dodge the pursuing fighters around space debris (unintentionally killing one), and hightail it to Yavin IV so he can personally warn Leia (who is visiting there), so she can go to Mon Calamari to recruit Admiral Ackbar, so they can send one lone battleship to Anoth to engage the Imperials capturing baby Anakin. After he is safe, Terpfen tries to kill himself out of guilt, but Ackbar decides to spare his life. Fortunate too because by the time they get back to Coruscant, Terpfen finally remembers that he helped poison Mon Mothma and tells them how to cure her. Again, this could have all been resolved much more quickly (not to mention prevented any risk of the Empire reestablishing their mind control link before he revealed his sabotage, Mon Mothma dying of her poison, the New Republic battleship being outgunned by an Imperial fleet of unknown size, or the Republic capturing Anakin and then leaving) if Terpfen had just walked down the hall on Coruscant and told the other New Republic leaders about what he'd done.
And what would have happened had Terpfen failed to hijack the ship? He would be taken into custody and asked why he did it, at which point he'd reveal the sabotage and things would be solved just as easily as if he'd told them in the first place!
Unless the guards just shot him (which they tried to do). Hence, idiot plot.
The Adventures of Archie Reynolds functions entirely because everyone is a moron. The plot involves three boys who discover a secret passageway, which eventually leads to stolen jewels and the rescue of a kidnap victim. However...
The door to the secret passage is out in the open where anyone could see it. That's how it's discovered.
The criminals left a clue leading to the combination to a safe right on the safe itself, assuming no-one would figure out the world's most obvious clue.
When the kids discover the jewels inside the safe and steal them, the criminals decide to recoup their loss by... kidnapping a random neighborhood girl, and keeping her hostage in the exact same area as their stolen jewels, which is how Archie discovers her.
Mary Shelley's Frankenstein. For all Victor's impressive scientific knowledge, he is an impulsive, self-centered idiot who never once plans ahead. He gets all wrapped up in creating the monster and makes no contingency plans at all for what might happen after he brings it to life. During Justine's murder trial, he just sits there looking stupid while his otherwise completely passive adopted sister acts as Justine's character witness, when he could prove her innocence easily (the time in a mental hospital that would probably result is peanuts compared to the life of an innocent). When the creature tells him to create a bride for him, Victor destroys the unfinished female rather than finish it out of fear that the two would reproduce (given the knowledge of human anatomy which we know he has, he could just "forget" to add a uterus and the problem's solved). Instead, his whole life gets destroyed and his loved ones are collateral damage. (Though the latter can probably be excused in that the young female author herself probably wouldn't have known about that particular aspect of human anatomy back in those days.)
For that matter, the Monster explicitly states his intention to take poetic revenge for his would-be bride (along the lines of "for having broken your word and denied me a mate, I shall take revenge on your wedding night"). Victor doesn't even think for a moment that maybe, just maybe, he's going to go after his wife and instead assumes the monster will just murder him, so he insists on being alone rather than endanger her, leaving her completely unprotected (and unwarned about a dangerous psycho who wants revenge). The only real defense of this idiocy is that the monster already killed Victor's actual love interest so maybe he's too grief stricken to think clearly about the threat he made.
The gamebook Search for the Nile. The protagonist, a contemporary kid, goes into the past; his quest? To find out what the source of Nile is. No, not to bear witness to its discovery, or anything like that; his mission is specifically to find out what the source of Nile is, and he treats it as a huge mystery he is desperate to unravel. Why couldn't the protagonist just look it up in an encyclopedia instead of going on a dangerous trip to untamed Africa is unexplained. Note that, in this series, the plot of each book is typically about unraveling some genuine historical mystery.
In Betrayed, Zoey sees red-eyed zombie-like vampires who she knew died as fledglings, hears about multiple students from her old school disappearing/turning up dead and drained of blood in the vicinity of the school (all of said students being people she knew who smoked pot, and whose names she gave to Neferet in the previous book), Neferet repeatedly tells Zoey that humans are worthless and she should cut them out of her life entirely, and Zoey catches Neferet kissing one of the red-eyed vampires. It's not until the last few chapters that Zoey learns that the red-eyed vampires are kidnapping and draining the blood of the humans and that they're under the command of Neferet.
Chosen would have ended a lot more quickly if Zoey would have thought to try a simple healing ritual on Stevie Rae. This solution is given as being so obvious that it went unnoticed, but still.
Pretty much all of Hunted. For starters, the End of the World as We Know It has just begun, Raven Mockers are potentially everywhere and anywhere waiting for them to venture above ground, the weather outside is blizzard conditions, so what does Zoey do? She goes outside with Heath to say goodbye. It just so happens that a Raven Mocker is outside (waiting for her specifically) and it then goes to attack Heath. Now Zoey could have done many things here. She could have summoned her elements immediately and attacked the Raven Mocker, or dragged Heath to her and headed back to the Depot, or headed towards Heath's car and used it for cover while she thought of something to do or screamed for help (what with Erik being relatively close by). What she does do is push Heath out of the way and takes the hit for Heath instead and almost ends up nearly dying because of it. Um What? The idiocy is further compounded due to the fact that Zoey has already fought off Raven Mockers before by using her elements.
Simona Ahrnstedt gives us a really painful example of this in her debut novel, Överenskommelser. It's the story about young Beatrice, who's bullied and pressured by her abusive and tyrannical uncle into an engagement with a man. A man who's not only like forty years older than her, but he also treats women like they're dirt under his shoes. So what does she do? Of course, she tells nobody the truth about why she agreed to marry this man (he would get her beautiful but weak cousin instead, if she didn't sacrifice herself). To be fair, she really is in a crappy situation, but still, yikes... And unfortunately, her love interest Seth is no better. Since he thinks that she willingly rejected him to marry an old disgusting aristocrat, stupid pride keeps him from admitting that he loves her. Several misunderstandings between them (sigh...) leads to much misery for them both (including that Beatrice gets brutally raped and battered on her wedding night).
Speaking of the piggies, despite being intelligent they apparently don't even consider the possibility that human biology isn't exactly like theirs, even though they know the human settlement doesn't have any trees in it.
Pipo's assistant Novinha, who's in love with Pipo's son Libo, can't figure out what Pipo did, and doesn't want Libo ending up dead too. Instead of simply making him promise not to run out to the forest and get killed confronting the piggies, she instead seals the files and begins a decades long campaign of silence, forcing them both to marry other peoplenote If they married, he would have access to her files, because apparently married couples in the future aren't allowed privacy from each other, or maybe this rule was made up to set up the plot and live a lie for the rest of their lives.
And then ironically, it still doesn't save Libo's life, who ends up doing exactly the same thing as his father years later. With all the attendant idiocy that implies. This whole mess turns out to be unkind to the piggies as well, since on learning that instead of honoring the two as great men and potential fathers, they had actually committed murder, the piggies are shocked and horrified, and admit they never would have done it if someone had only told them.
Of course, considering that the piggies are stated to be at least as intelligent as humans and possibly more intelligent on average, it boggles the mind that after they attempted to plant Pipo and it didn't work— no new tree growing in the forest to sire children, no new voice in the fathertrees' telepathic chat room— they go ahead and do the same to Libo, instead of thinking, "Holy crap, we've made a terrible mistake, we fucked up the ritual somehow and accidentally killed our friend, we'd better think long and hard before we try it on another human." There's something in there about how they thought the humans had prevented Pipo and Libo from becoming trees by carting off their bodies before they could take root. But when a piggy undergoes this, the tree starts sprouting immediately, while Pipo and Libo just lie there dead for some time before they're found.
Novinha keeps the plot going by still refusing to share her notes with anyone, even though it didn't save Libo.
A lot of World War Z, even leaving aside the zombies' plot armor, relies on this, most infamously the Battle of Yonkers. Artillery and weapons are used at ludicrously short range, the army somehow doesn't pack enough ammo despite that being basic logistics, they don't have air recon, aerial bombardment is the last resort instead of the first, a bunch of expensive, useless gear, and it's even kvetched about by the character narrating. The explanation? It was a "propaganda battle" designed to look good in front of the cameras, not to actually follow centuries of established military doctrine. Which doesn't explain why they didn't just fight the battle in a competent manner and then cut it together later. Some of the plot is stupendously unlikely, such as the networked information system conveniently broadcasting a soldier's camera feed to everyone in the combat zone just as he's attacked by a zombie. Which lowers morale.
It's mentioned that someone figured out how to kill zombies by going up to the roof of an adjacent building and making noise so the Zachs walk off the roof trying to get to them. The "someone" was a dog. No mention is made of humans making use of similar tactics.
The story would probably have finished a lot sooner if Nora would have just told her mother that she was being harassed and stalked, or reported Patch and her Biology teacher to the school Superintendent (both of whom were violating the School Code Book, promising all students safety on school grounds).
Of the many people who try to kill Nora, they all fail because they waste time stalking her for no reason instead of just killing her. It's especially bad in Crescendo, when even Nora notes that the bad guy had no reason to spend weeks having her on and off hallucinate her murdered father in some sort of forgettable attempt to psychologically torture her. The only reason given is that he wanted to enjoy himself before killing her. It's arguable as to how well that explanation works, but it still doesn't explain why he pauses before actually killing her - away from all witnesses and with a gun pointed at her - to answer all of her questions as she stalls for time. Sure enough, this leads to Patch and Scott showing up and saving her.
In the later books, the entire fallen angels vs. Nephilim vs. archangels conflict (the driving force of Silence and Finale) becomes this when it's revealed that the archangels have a feather from every angel ever banished and burning said feathers sends that respective fallen angel to Hell. With no fallen angels running around on Earth, there are no more Nephilim! Problem solved! Even if someone is willing to argue that it's wrong to throw every fallen angel ever into Hell, that doesn't explain why the archangels make no effort to track the fallen angels and send them to Hell if they're caught actively siring or birthing Nephilim (whom the archangels hate, for reasons never really explained).
WICKED's plan in The Maze Runner Trilogy is basically this: instead of studying the Immunes actual immune system (the part of the body responsible for fighting diseases) they instead focus on mapping their neurological system (that is, the part of the body responsible for making decisions, and feeling emotions, and interpreting data, and making you "you") and never once do they realize that not only are these bodily systems completely unrelated, but that even if they could analyze the human brain to the point where they could copy its layout into another human being, it still wouldn't do anything because the body is dying of a disease, which is why the Immune are immune: their immune system is independent of the brain. WICKED should have studied that much more understood part of the body, but if they had, we would have no plot.
Futuristic Violence and Fancy Suits doesn't look like an Idiot Plot at first glance, but after a few of the central mysteries are revealed, you realize:
In spite of their desire to check everything in the Vault for what Arthur might have left, they never think to check the coin for data storage even though they are clearly aware that data stores can be that small. To be fair, Will hangs a lampshade on it afterwards.
After this, a significant portion of the plot and multiple fatalities could have been avoided had they thought to scroll down to the bottom of the directory on the coin drive, even though the team's "Computer Expert" reports having completely analyzed it!
The Honor Harrington series has a shining example in the ninth book, Ashes of Victory. Mueller gives Queen Elizabeth and Duke Cromarty each a "memory stone" to wear on a chain around their neck. Later, they have a whole conversation about how nervous Mueller seemed, and oh yeah, he's under investigation for possible treason. "Gee, these stones he gave us sure are pretty." Even the bodyguards whose job it is to be suspicious express no reservations about that. Granted, they might not have guessed that the stones contained beacons for missiles to home in on, but they might have figured that Mueller was up to something. If it weren't for this, the entire rest of the series would have been very different.
The Client has Mark learn the location of the murdered senator's body simply because he repeatedly kept trying to interrupt Romey's suicide, instead of leaving someone obviously very determined to end their life alone. The rest of the book follows him carrying around this knowledge and trying to dodge the FBI, who want him to reveal the body's location, and the mob, who threaten to kill him for talking. In the end, the senator's body and its location are revealed and Mark is sent off into the witness protection program - something that his lawyer could've told him to be the likely safest option to choose from the get-go.
The characters of the Winnie-the-Pooh franchise are supposed to be child-like, but sometimes it can be hard to not feel that they're just simply being idiotic. The franchise is all about an ode to silliness, after all. A number of things that happen in Pooh's Heffalump Movie are a prime example, particularly the fact that only Kanga and Roo seem to be capable of realizing at first that Lumpy is just a scared little child who wants his mummy. Also, Roo finds him almost right away, while for a good portion of the film the rest of the gang bumbles around the heffalump forest like morons.
The plot of P.D. Eastman children's book Sam and the Firefly relies on humans immediately following instructions that suddenly appear in front of them (courtesy of the eponymous firefly, Gus, writing words with his light), resulting in numerous car accidents, airplanes flying around crazily in the sky, and causing a hot dog stand to lose its customers when Gus writes Cold Dogs over the hot dog sign. (Specifically, said customers believe that the hot dogs that they are currently eating are "cold dogs" after reading Gus's writing and vacate the premises.) Later, the man who was running the hot dog stand has his truck stall on some train tracks as a train is approaching and doesn't appear to run away from the approaching train at any point.
Samson and Delilah from The Bible: Samson is clueless that Delilah can't be trusted after she repeatedly tries to weaken him and spring the Philistines on him. He ends up telling her the secret of his strength.
Where's Rufus? starts off a family deciding to go a picnic in the afteroon. When noon comes in, it starts to rain and apparently, only the dog, Rufus, is aware that it's raining. He then hides, which alerts the family when they are ready to go outside. If they did know that it was raining, they would have delayed the picnic without trying to find Rufus.