Oh! what a tangled web we weave When first we practise to deceive!
— Walter Scott, Marmion (Canto VI. Stanza 17)
A suspicious character, thinking a friend or loved one is lying, goes along with the lie, forcing the liar to expand upon the cover story in a grossly outlandish fashion. Named for "pull the thread, and watch the sweater unravel."
In a comedy series, this can result in a Fawlty Towers Plot situation. In a drama, it results in the catastrophic collapse of a villain's house-of-cards scheme. May result from Spotting the Thread. Not to be confused with All Cloth Unravels, when literally pulling a single loose thread on a piece of clothing causes the whole piece of clothing to come undone.
Contrast Seamless Spontaneous Lie. Compare and contrast Conviction by Contradiction, which skips the "pull the thread" step and jumps straight from catching a lie or mistake to assuming guilt of some greater crime.
Used with Col. Jessup in A Few Good Men. Tom Cruise's character continues to question Jessup until he catches Jessup in a contradiction: Jessup had ordered that Santiago was not to be harmed, and assured the court that his orders were always followed, to the letter. Thus, the Armor-Piercing Question from Cruise says that if that were true, there would be no reason to transfer Sanitago off the base, as Jessup did, because Santiago shouldn't have been in any danger if Jessup's orders are always followed. It's the slight Oh, Crap moment from Jessup which follows that begins to unravel his entire testimony.
The film Shattered Glass has editor Charles Lane asking reporter Stephen Glass to retrace a sequence of events reported in one of the latter's (completely made-up) news articles. Glass picks a building and a restaurant more or less at random, then has the spectacularly bad luck of discovering both were closed at the time the events in his article supposedly took place. The trope is eventually subverted because no matter how many blatant lies Lane catches him in, Glass never capitulates and continues to spin how it could have happened (supposedly it happened this way in real life as well).
The ending of the 1974 version of The Taking of Pelham 123has the last remaining hijacker accidentally giving away his identity with his recognizable sneeze.
Recall the elegant subversion in To Kill a Mockingbird: Atticus successfully pulls many threads in the Ewells' story of how Tom raped Mayella, particularly in the disparity of Mayella's bruise and Tom's handicap but the all-white jury ends up finding him guilty anyway.
In Lois McMaster Bujold's Vorkosigan Saga novel The Warrior's Apprentice, Miles invents the "Dendarii Free Mercenaries" out of whole cloth as a quick cover story. Then the new "provisonal members" start to inadvertently Pull the Thread , so he adds more detail. By the end of the novel there actually IS a Dendarii Free Mercenaries, uniform, field manual, hidden government backing, and all. The majority of it essentially made up on the spot by 3 terribly overworked people.
Live Action TV
Every last Columbo episode revolves around Lt. Columbo pulling the threads in the culprit's story.
It's pretty clear that Britta in the Communitypilot has caught early on exactly what kind of guy Jeff really is, but is stringing him along until he can demonstrate it in front of everyone.
The Doctor in Doctor Who loves doing this. In "Amy's Choice," he sums up his mission (and life philosophy) in two sentences: "Something's not right here. Let's go poke it with a stick..."
Everybody Loves Raymond: Ray lies to cover up the fact that he didn't want to have dinner with his mother, Marie. To keep up the lie, he arranges a cover story with his wife. It snowballs until he ends up breaking the VCR and the washing machine, but she figures it out anyway when they run out of lies. Hilariously, Robert's wife Amy confesses to not eating the dinner Marie made them after watching her pull the thread and guilt-trip Ray, because "it's only a matter of time". Then a verbal slip from Marie reveals to Robert that she didn't actually make a special meal for him, she made it for Ray.
Used on Friends to get Chandler to admit he is in a relationship with Monica by having Phoebe come on to him.
Also, Monica warns Chandler against a similar danger when he sees a photograph of himself making his "bedroom eyes":
Chandler: Oh my God! Those are my bedroom eyes?! Why did you ever sleep with me?
Monica: Do you really want to pull at that thread?
How I Met Your Mother: One episode featured Robin revealing that she had an unusual fear of going to the mall. The other members of the group form theories as to why this is. Marshall believes it's because she got married at a mall when she lived in Canada. Not wanting to reveal the real reason, Robin decides to use this as her cover story. Ted decides to test her on it and asks her numerous detailed questions about her wedding, all of which Robin easily answers, but then blows it when she's suddenly unable to think of an answer when Ted asks her the simplest question, what the groom's name was.
The implication seems to be that like a lot of (mainly female) people, Robin has a pretty solid plan of what she wants her wedding to look like, with just a couple of details to be filled into the blanks.
Robin does this again when she tells them that they were right in thinking that she slept with a rather dumb guy after a Halloween party and thus did not have time to change out of her costume before the next morning. When the lie unravels we find out that she was still in her nurse uniform costume because it was actually for an adult diaper commercial she filmed.
Pulling the thread on It's Always Sunny in Philadelphia leads to Frank and Dee (father and daughter mind you) almost getting married just to keep up the lie that they were in a relationship in order to scam some money.
In LOST, Sayid interrogates a captive who claims to have reached the island by balloon. How big was the balloon? How did he afford it? What was the business he sold?
Except the captive answers all the questions in a self-consistent manner. Sayid thinks that he's probably lying, but can't tell for certain. He turns out to be the leader of the Others, Benjamin Linus.
Narrowly averted on Raising Hope after Virginia tells her cousin Delilah that Maw Maw has died just so Delilah would not come for a visit and see what a mess Virginia's life was. A few years later Delilah comes to town to see if Maw Maw left her anything in her will and Virginia starts spinning more lies to hide the truth. Delilah never finds out the truth because she is more interested in screwing with Virginia than pulling more threads. When she actually sees Maw Maw alive and walking she assumes it is a ghost come to punish her for being such a Jerk Ass.
In Seinfeld, George's desperation not to spend time with his once-potential parents-in-law at a function they have arranged sees him concoct a story about owning a luxurious house in the Hamptons which he is spending time at, and ends with him driving them all the way to the Hamptons to keep the lie going. When he breaks down and admits the truth, they confirm they knew all along, but let him suffer through keeping up the charade because they don't like him very much.
Emily can't stop herself from pulling the thread in her S4 episode of Skins; it starts with Naomi telling one small lie to the police and ends in The Reveal that Naomi cheated on her at a university open day.
The usual tactic used on the BBC panel show Would I Lie to You?, where the panelists present facts about either themselves or other famous people/events and the other team has to guess if they're telling the truth. Most lies collapse when the liars are pushed for information they haven't invented and contradict themselves. That said, being confused or vague doesn't always mean they're lying...
The Buffy the Vampire Slayer third season episode "Faith, Hope & Trick" provides an interesting twist to this trope; Giles isn't trying to catch Buffy in a lie, he's trying to get her to reveal her Dark Secret - that Angel got his soul back, but she had to kill him to save the world. Giles gets her to reveal this by asking for details about that day for a "binding spell" he needs.
In Brooklyn Nine-Nine, Detective Santiago has a tendency to try and suck up to Captain Holt in order to curry favour and try and persuade him to act as her mentor. Since Captain Holt isn't particularly fond of Yes Men, he instead tends to use this trope not so much to expose her insincerity (since she does genuinely respect him) but instead to expose the false modesty and flaws in logic that she ties herself in while doing so.
This is one of the rules of the storytelling game The Adventures of Baron Munchausen. One player starts to tell the most outlandish story about his adventures (Such as the time a pair of Frenchmen took credit for his invention of the hot air balloon), and the other players repeatedly interrupt him with additional questions. The storyteller has to either incorporate them into the story or pass the turn to the next player.
Oh, Oedipus, you just had to pull the thread yourself.
Episode 1 of The Wolf Among Us features Bigby going to Toad's apartment with the place clearly ransacked, while Toad insists that he kept hurting himself trying to get into his apartment last night. Bigby can, if the player chooses, continue to call out the contradictions in Toad's story, until Toad reveals he was covering it up under threat of assault.
During the Clear My Name quest of Neverwinter Nights, Chapter 2 you come across a "witness" who is obviously falsifying his story. Only by pulling the thread of his story can you get him to admit he was nowhere near the scene of the murder.
In Dragon Age: Origins, there is more than one way to reveal the fake Weylon. One, you just get too near a certain door and refuse to leave. The other is tricking him, intimidating him and forcing him to expand on his story while picking out all the mistakes he makes until he finally merely gets irritated and attacks.
In the 1st Degree goes into this trope when it comes to questioning the witnesses: Why were you seen searching the body after the shooting? You were just trying to do CPR? Why would you do CPR if the victim is dying from a bleeding neck wound?
Pulling the thread is an integral concept in the Ace Attorney series. In most cases, it's not a matter of playing along with the lie, but of catching the lie and then forcing the person you're questioning into making up a lie to cover up the lie ("No, wait! I was mistaken!"). In at least one case (Mr. Kudo), this actually comes back to bite Phoenix, when he really should have convinced the court to listen to the person he just completely discredited.
This is essentially the point of the "press" option: if you can't see anything contradictory in the witnesses' current statement, you can ask them to elaborate, which quite often leads to them saying something that is contradictory, which you can then call them on.
In CLANNAD, pulling the thread on one of Sunohara's lies leads from how Sunohara's parents will get worried if they're out too late to the invention of an illegitimate adult son for the 23 year old Sagara Misae. Said son is named Sagara Missile. And to make things worse, Sunohara then nicknames Tomoya Apache and Tomoyo The Ultimate Weapon. But it works out okay because they still go and do what he wanted.
In My Forged Wedding, Takao asks the Player Character to pose as his fiancee, because his grandmother's health is failing and it would make her happy to know that Takao found someone to marry. Then his grandmother's health takes an unexpected turn for the better, and she begins making plans for the wedding. Only after they've held a wedding ceremony does she admit that she figured out the truth early on and kept stringing them along mostly in the hopes that they'd fall in love for real.
Dr. Irie in Kiss Of Revenge rarely confronts the protagonist directly over her suspicious behavior, and even when he does he never reveals everything he knows. His preferred modus operandi is to play along, hinting just enough of his suspicions to put her on edge, occasionally dangling some bait in front of her to see what she'll do, and generally giving her rope to find out whether or not she'll hang herself with it.
Turned up in an episode of Cyberchase; TheHacker is running for president of Cyberspace, on the platform of "I'll cure Motherboard of that nasty virus I gave her" and mentions that doing so involves a triangle, which can be made with any three lines. When the Power Trio proves that not all lines can form (closed) triangles, everyone immediately stops believing Hacker and agrees with the kids.
Miss Manners actually recommended this tactic for dealing with a woman who always has to top whatever story you tell. If you say your wife just had a baby and she brings up a relative who just had triplets, Miss Manners advocates playing along with fervor: "Oh, how wonderful! When were they born? What are their names? How big were they? Did they have any medical problems? I hear triplets can be low birth-weight and need a respirator for a few weeks..." etc. Until she runs out of ammo, or realizes what you're doing, at least you're having as much fun with it as she is.
This is a common cross-examination technique. In most Western legal systems, lawyers aren't allowed to directly accuse a witness of lying as a challenge. The solution is to pull the thread until an inconsistency, either with evidence or prior statements, comes out. This can then be waved about, usually discrediting the witness in the eyes of the jury.
Also a common police interrogation technique. Many confessions have come after the interrogator first gets the suspect to admit to a small lie ("Yeah, okay, I did know him") and then going from there.
Unfortunately, it's just as easy to get an innocent person to confess with this method as it is a guilty person, which is why Americans are advised to invoke their Fifth Amendment rights and ask for their lawyers even if they are innocent.
Socrates did this with style and to some people he probably shouldn't have screwed with, although in his opinion it was his duty to do so, and he insisted that he really just wanted to learn instead of just being a dick. The Socratic method owes its name to his rhetoric. It should be noted that Socrates wasn't uncovering lies per se, but hypocrisies. And that he ended up highly dead.
Louis CK's stand-up routine about kids asking "why?" and how you should understand when their parents tell them to shut up, because "they just keep coming, more questions, why, why, why, until you don't even now who the fuck you are anymore at the end of the conversation!"
"Papa, why can't we go outside?" "'Cause it's raining." "Why?" "Well, water's coming out of the sky." "Why?" "'Cause it was in a cloud." "Why?" "Well, clouds form... when there's... vapor." "Why?" "...I don't know! I don't know. I don't know any more things. Those are all the things I know." "Why?" "'Cause I'm stupid. Okay? I'm stupid." "Why?" "Well, 'cause I didn't pay attention in school, okay? I went to school but I didn't listen in class." "Why?" "'Cause I was high all the time! I smoked too much pot!" "Why?" "'Cause my parents gave me no guidance! They didn't give a shit!" "Why?" "'Cause they fucked in a car and had me, and they resented me for taking their youth!" "Why?" "Because they had bad morals! They had no compass!" "Why?" "'Cause they had shitty parents! It just keeps going back like that!" "Why?" "'Cause, fuck it, we're alone in the universe!..."
In mathematics and logic, there is proof by contradiction—one way of proving something is to assume the opposite is true, and follow the consequent trail of reasoning until you arrive at an obvious fallacy. For instance, one can reason that 1 = 2, but only if somewhere along the way they divide by zero. Since you end up with a contradiction, this shows that the original premise (that the opposite of what you wanted to prove was true) was actually false, and hence what you wanted to prove is true.
Debunkers of phoney psychics sometimes exploit this approach, "giving away" fake hints to their identity and then watching as self-proclaimed fortune-tellers talk themselves into a corner, building upon such bogus leads.
Works well when you suspect that your spouse or significant other might be cheating on you. Watch for changing stories and half-truths, commonly known as "trickle truth."