<lights go out>
Detective: Good. Now then, there was a scream, <screams>, and then, just before the lights went up, there was a shot.
<Gunshot sound effect. The lights come on, revealing the detective dead, with an arrow in his neck>
This trope describes the basic situation where a story's characters are attending a Masquerade Ball, a dinner party, or any event with a sizeable amount of people in it, and the lights go out. Usually this is accompanied by screams, chaos and people trying to feel their way through the dark, but, more importantly, as soon as the lights come on someone is found to have been murdered in all of the commotion.
The general reason for this trope is often to establish a mystery where, in the dark, anyone could have done it.
In Real Life, this kind of murder would be very difficult to actually pull off, unless animals are used. The murderer would have to be able to see in the dark, in order to avoid tripping over things or bumping into people. Then they would have to correctly identify the person they want to kill without seeing their face. (This sometimes leads to a plot twist where it turns out that somebody else in the room was actually the murderer's intended victim.) They'd also need to work out how to discreetly get the lights off in the first place - everyone is going to suspect that shady-looking fellow who was hanging around the light switch. Best not to think about it too hard.
Compare Darkness = Death, where the lights are already off.
- Quite a few murders in Detective Conan rely on this trope, including one subversion where it turns out the act of turning the power back on is what actually kills the victim. ( Poor Hikaru Yasumoto, killing her boss without even knowing it!)
- In Detective School Q, there's a murder while a Phony Psychic has the lights turned off as part of a ritual. She was strangled by the sons of the family since they thought she was an accomplice of their Evil Aunt who wanted to go the Financial Abuse on the heiress and their little sister. She turned out to be their mom under a disguise.
- During the final part of the Hunter side story to Mother Keeper the lights suddenly go out and everyone except Silas suddenly drops dead.
- One of Kindaichi Returns Series' cases, titled "Black Spirit Hotel Murder Case", combines this trope with Falling Chandelier of Doom. In the middle of filming a horror movie, a chandelier falls down after a blackout occurs and kills an actress sitting below it, making people believe that the culprit is someone not present during the shoot. In reality, the killer replaced the screws holding the chandelier up with an electromagnet beforehand. This way said chandelier will surely fall when blackout occurs.
- A rather ambiguous example from Calvin and Hobbes: The Series: the climax of the final story (which involves Slender Man) has the lights going off when he shows up. Twice, after they come back on one of the story's antagonists is gone, with absolutely no explanation as to what happened. The second time, said antagonist's screams heavily imply he was really dying, however.
- The Empath: The Luckiest Smurf story "A Haunted Christmas" plays around with this, as after Smurfette tells her story of the first Christmas she spent with the Smurfs, the lights go off at the Christmas dinner, and Smurfette inexplicably disappears without a sound. The story ends leaving Smurfette's fate ambiguous.
- Despair's Last Resort appears to have one in Chapter 4. During breakfast one morning, the power goes out and Minoru Yoshihara is found dead with a knife in his back. This leads them to believe someone navigated through the dark and stabbed him. In the end though, it turns out the knife was only a ruse to distract from the real cause of death: bleach poisoning. Minoru was dying before the lights went out.
- Mr. Boddy's murder in Clue. Mr. Boddy's actually the one who turns off the lights, expecting everyone in the room to attempt to murder someone else. It Makes Sense in Context.
- And he was actually faking his death because he realized someone was trying to kill him instead. Said guest succeeds later, but not in the dark.
- Also, later in the movie when the power in the mansion is shut off, three more murders take place.
- Subverted when Wadsworth is illustrating how the murders took place. He shuts off the lights, Peacock screams, lights come on, Wadsworth drops forward rigidly...then catches himself and continues his energetic summation.
- In Devil, nearly every time the lights go out in the elevator, someone gets murdered.
- The Three Stooges often parodied this trope, when during brawls someone would turn out the lights, and when they were turned on again the fighting parties would be in a funny position, or the Stooges would be accidentally beating each other up.
- Used to the point of a Running Gag in Dark and Stormy Night. At one point, during the brief blackout, Jack Tugdon is killed, his head taxidermied, and mounted on a wall. Towards the end of the film, the characters aren't even surprised anymore.
- Played with in A Shot in the Dark. Inspecter Clouseau has gathered the suspects for The Summation, but he has no idea who the killer is. He arranges for his partner to turn off the lights, so the guilty party will take this opportunity to escape. They then get into a dispute over when he was supposed to turn the lights off. Eventually Clouseau rambles on so much the killer confesses anyway It turns out everyone in the room except the main suspect was involved in one murder or another. When the lights do go out, it interrupts Clouseau's attempt to arrest them and they all flee and get blown up by a car bomb meant for Clouseau.
- In The Phantom of Crestwood, the killer causes a fuse to blow, plunging the sitting room into darkness. While the lights are off, they attempt to stab Esther with a dart. However, in the dark, they miss her neck and stab her in the shoulder.
- In the Miss Marple novel A Murder Is Announced, a personal ad appears in the town newspaper, announcing that a murder will take place in a certain house at a certain time, and inviting everyone to come over. The Genre Blind locals assume the ad is inviting them to a party game (sort of "Murder in the Dark" for adults) and attend. Naturally, the owner of the house claims to know nothing about the ad, and then at the right time the lights go off...
- Something of a subversion considering the person who is found dead is the person who was waving the gun around.
- In Baynard Kendrick's novel The Last Express a killer stabs a man to death in a night club and no one notices because the room was bathed in red light for a performance and you can't see red blood under red light.
- The Anno Dracula novella "Vampire Romance". Deals with some of the usual objections: All the suspects, being vampires, have (or at least may have) supernatural speed and the an ability to see in the dark; and the lights go out due to an existing intermittent wiring fault.
- Happens during a game of Murder in the Dark in the Ellery Queen short story "The Dead Cat" in Calendar of Crime. The fact that the murderer was able to commit the crime in a pitch black room is what clues Ellery in to the solution.
- Holly Black's short Doctor Who story "Lights Out" fits this trope to a tee — during mysterious Thirty Second Blackouts at the Intergalactic Coffee Roasting Station, a killer is preying upon innocents waiting for their caffeine fixes. The Twelfth Doctor has to figure out how the blackouts and killings are possible. The culprit is a creature with a Superpowered Evil Side that only emerges in darkness, whereupon it's able to see its victims, and has engineered the blackouts.
- In Phantoms by Dean Koontz, there's a scene where the group enters a grocery store. The lights suddenly go out, and one person is snatched away in the darkness and killed. Interestingly, most of the scene is told from the point of view of the guy being taken away.
- Doctor Who has the Weeping Angels, lifeforms that actually function by this trope. They exist as statues when being observed, and only when no one is looking can they move. When the lights go out, they can move almost instantly from place to place.
- This also happened in the episode "The Unicorn and the Wasp."
- Star Trek: The Original Series episode "Wolf in the Fold". While a seance is going on to find out who the murderer is, the flame that's the only light in the room goes out. The medium running the seance screams, and when the light comes up again, she's dead: stabbed in the back.
Morla: The lights were out. Anyone would've had time to kill the lady.
- One episode of The X-Files had an enemy that would only attack in the dark.
- The Foyle's War episode "The White Feather". In that case the killer had to arrange for the victim to be holding a lit cigarette, to be used as an aiming point in the dark.
- An episode of Family Matters has an imaginary parody of detective works with Urkel as the detective. Every time Urkel would accuse someone of the murders, thunder would make the lights go off briefly and that person would be found dead. Laura is the murderer.
- Parodied in Monty Python's Flying Circus. In one sketch the lights go off and a police inspector is killed. Another police inspector enters and decides to reconstruct the crime. Once the lights are turned off, he is killed as well. The scenario repeats until there's a large pile of dead police officers in the room.
- Used in the slasher-themed episode of Boy Meets World.
- Used in Tracker. One of the fugitive aliens cut the lights in the Watchfire, then killed someone while the lights were off.
- Happened once on Dallas. When the murderer was confessing to their crime, they said this was actually a coincidence. The victim had had a poison inside them long before the lights went off. This example also subverts Perfect Poison.
- Parodied in a Wayne and Shuster sketch. Sherlock Holmes and Watson are holding a Summation Gathering in a stately country home. Every time that Holmes dramatically announces who the murderer is, the lights go out. When they come back on, the suspect he has just named is dead. After all of the suspects have been killed, Holmes deduces that he must be in the wrong house.
- Parodied in one sketch of Studio C with a Mystery Theater theme. After Jason learns that the lights temporarily turn off every time lightning strikes nearby, he tries to kill guests when this happens. However he can't get the timing right - he keeps killing guests after he sees lightning, but before the lights actually go off, in full view of everyone else. Despite this, each time when the lights come on he tries to blame it on the butler.
- The Doctor Blake Mysteries: Happens in "The Visible World" when Lucien confronts Major Alderton at the Ballarat Observatory. As the observatory is plunged into darkness by a partial eclipse, there is a gunshot and when the lights come up, Alderton is lying dead at Lucien's feet.
- Murder, She Wrote: Seemingly happens in "Test of Wills". When the lights go out during a storm, everyone scatters and then a shot rings out. When the return to the den, they find the patriarch of the family sprawled on his desk, seemingly having been shot through the head. However, this turns out to be a case of Faking the Dead.
- Leverage: "The Ten Lil' Grifters Job" has the team infiltrating a murder mystery party where the host gets murdered during a lightning-induced blackout. This sets Nate's mind turning, as he realizes that every other time there was a lightning strike then an outage, but that time the lights went out before the lightning strike. It turns out the culprit was the police detective there, working with the host's daughter. She killed the lights, while he killed her father.
- The Muppet Show: One episode had the Muppets putting on a murder mystery which ends with this scenario. When the lights come up Liza Minnelli is found with a knife in her chest, and dies in a dramatically overblown scene. Statler and Waldorf then appear lamenting that they weren't trying to get her, they were after everyone else. Liza gets up, pulls the fake knife from her chest and points accusingly at them.
- Midsomer Murders: In "Written in the Stars", the Victim of the Week is part of a gathering observing a total eclipse. As the hill is plunged into total darkness by the eclipse, he is bashed over the head by a rock. A bystander screams as the sunlight returns and she sees the body.
- Miss Fisher's Murder Mysteries in the second season episode "Framed For Murder" uses this in a movie studio.
- The song Dangerous Dan McGrew. Barbershop quartets sometimes sing a variation, part of which goes:
And then suddenly there, all the lights went out, and a voice cried "Die you must!"And a shot rang out and a woman screamed. Somebody bit the dust!Then the lights flashed on and the Northwest Mounted Police came a crashing throughAnd they drew their guns, and they said "Which one is Dangerous Dan McGrew?"
- Very common in Pro wrestling, the most notable examples including The Undertaker and Sting. Lights go off, gong sounds, lights come on, and either 'Taker mysteriously appears in the middle of the ring or someone who was already in it is incapacitated by 'Taker. Sometimes justified as Undertaker having vague electrical powers or in a case involving Homicide, a power stable which had infiltrated Ring of Honor and helped him pull at least one attack in the darkness.
- If this isn't happening at least once per mission in Paranoia, you're not playing it right.
- Inverted in Calm Time, an Indie horror game about Six Little Murder Victims in a party in a countryside house. First, the first victim is stabbed and killed when the lights are still on, then the killer kills the power in the house, switching all lights off.
- In Five Nights at Freddy's, the somebody in question is you. When you run out of power, your doors will open and there will be only a sliver of light. Freddy shows up outside the left door with only his eyes illuminated, playing the Toreador March. Once that's done, the screen will go entirely dark. If the clock doesn't tick over to 6 AM right then, Freddy kills you.
- Double subverted in the first case of Super Danganronpa 2. The lights go off at a party, and when they come back up we see... Mikan fell down again. A few minutes later, a corpse turns up.
- Happens again at one point in New Danganronpa V3, but it's somewhat downplayed since there isn't a blackout this time. Instead, some of the students are performing a necromantic ritual where one of the requirements is a completely dark room. The ritual fails, so the lights go back on...and someone turns up dead.
- Subverted in Ace Attorney Investigations: Miles Edgeworth 2, when Edgeworth, Gumshoe, and Kay are on an airplane with an assassin when the lights go out. They aren't his target, so he merely administers a Tap on the Head and escapes.
- Death Battle did this during Batman vs Spider-Man when Batman decides to kill Spider-Man by turning off the lights in a building. Considering what the Spider-Sense can do, Batman is having trouble doing this.
- Invoked In-Universe by Bart Simpson. After telling his class mates a ghost story, he reassures them that Dark Stanley would never dare attack a crowded, well-lit -- The lights go out, then back on, and Bart is "dead" on the ground with exposed brains.
- In the first "Tales of Interest" episode of Futurama, Leela's last four victims are all killed this way.
- The South Park episode "Cartman's Mom Is Still A Dirty Slut" begins with Dr. Mephesto being shot in the chest. It becomes the focus of the entire episode.
- In the Codename: Kids Next Door episode "C.L.U.E.S.", Numbuh Three's Posh Party Rainbow Monkey is stabbed in the back this way.
- In the episode "Mystery Train" of Adventure Time, it's exaggerated and subverted. A lot of candy people die on the train one by one as the lights go off, leaving nothing but skeletons. Finn tries to solve the mystery, while it turns out that no one actually died; it was a birthday surprise set up by Jake, all the skeletons are fake, and the prime suspect, the Conductor, was Jake in disguise.
- The same thing happens to Cinnamon Bun in "The Creeps". Once again, it's all a prank.
- In the Family Guy episode "And Then There were Fewer", when everyone accuses James Woods of being the murderer, the lights go off and then back on to see that Woods has been stabbed.
- At the end of "Twelve and a Half Angry Men", Stewie notes there's still a maniac on the loose cutting peoples' power and killing them. When the lights go off, Stewie flatly says "We're dead".
- One episode of Celebrity Deathmatch, that pays homage to Scream, has a segment where corespondent Stacy Cornbred is interviewing Drew Barrymore, when suddenly the lights switch off, followed by a scream, before the lights come back on to reveal that an unknown killer had crushed and slashed Drew's head.
- The children's game "Murder in the Dark" is based on this trope.
- There is a story about Mixed Martial Arts fighter Rickson Gracie facing an opponent nicknamed Magno in a grappling match. Supposedly, lights went out during the bout just when Magno had the upper hand, and when they fixed it, Gracie had won.