There are very few situations that warrant an "Oh, Crap!" quite as much as waking up in the villain's Evil Lair. The reasons are many and obvious, but this wouldn't be TV Tropes if we didn't analyze 'em all!
For starters, the place is probably full of Death Traps, and the owner is likely not far off and just waiting to sneak up on the intruder at just the right time. That they've been brought to the lair alive is seldom good news, he "has you now, pretty!" and can intend anything from marrying, killing, eating, mating, or wearing the captivenote . Fun times.
If that isn't nerve wracking enough, the villain and/or monster might be sleeping not-very-soundly among the memorabilia and leftovers from their last kill. If the hero is really up a creek, he or she will wake up next to said villain, with the latter keeping a paw on them or wearing the only key to the door out around their neck.
Which makes the idea of a free character willingly exploring the lair once they find it (and alone, which is usually the case) all the more bizarre. Of course, exploring the lair represents an enormous opportunity. If they don't know who has been killing them off, or how to kill the unkillable, exploring the lair represents a treasure trove of clues in the form of finding a Stalker Shrine, Shrine to Self, Supervillain Lair or other clues to their identity/weakness (remember, villains always keep the one thing that can harm them in their lair). It can also present them with the irresistible and incredibly dangerous chance to attack the villain or monster in their sleep. Thus characters are advised to Never Split the Party; threaten to leave The So-Called Coward to wait alone to get him to cooperate, if necessary.
Typically, whoever is doing the exploring may be unlucky and killed or captured, or get lucky and manage to hide from the villain and escape in a tense and nail biting sequence (or think they did, only to have their arm bust through a wall and catch them). Usually, they get just as far as the threshold before the one, tiny soundnote wakes it, or it shows up at the doorway. Survival varies by victim, of course.
- Dragonslayer, when Galen entered the dragon's lair to rescue the princess.
- Legend (1985). Jack and his friends enter Darkness' lair to rescue Lili and the unicorn.
- In Alfred Hitchcock's Rear Window, Jeffries (convalescent with a broken foot) helplessly watches his girlfriend Lisa checking out the villain's
- In Return to Oz, Dorothy going into the witch Mombi's original head case to get the key and powder of life. Of course, the head wakes up and screams like a living nightmare.
- In The Silence of the Lambs, Clarice Starling winds up playing hide-and-seek with "Buffalo Bill" in his basement to find a hostage, instead of getting out and calling for backup.
- In The Ghost and the Darkness, the two protagonists investigate the lions' den, filled with the remains of their human and animal victims.
- In Mickey, Donald, Goofy: The Three Musketeers, Donald is kidnapped and brought into Captain Pete's lair, where he discovers his plot to seize the throne and notices headstones reserved for him, Mickey and Goofy.
- Trench 11: The Allies send men to investigate what is believed to be the headquarters of Reiner, an infamous weapons scientist responsible for Deadly Gas.
- J. R. R. Tolkien did this a couple of times:
- Memory, Sorrow and Thorn: Simon, upon his return to the Hayholt, with specific attention to Hjeldin's Tower, which has become Evil Sorcerer Pryrates' lair. The latter is not present when he does it, but the book pulls a Chair Reveal with King Elias, who ends up releasing Simon, which then turns into a Hope Spot when he's captured by the returning Norns and thrown into the forge dungeon.
- In Buffy the Vampire Slayer Willow is taken to the Mayor's office and guarded by one incompetent vampire. After she escapes she starts looking around for information on his plans. She's caught by Faith, who quite rightly mocks her for "Nancy Drewing" instead of escaping.
- In The Prisoner (1967) No 6 wakes up in the village and slowly gets to realise how good a trap it is.
- Scream: In "Aftermath", Noah, Audrey, and Emma discover Ghostface's lair in an Abandoned Hospital. Noah geeks out about this, explaining how the "psycho killer's lair" trope is so prevalent in fiction, but then points out that it's only in fiction. Real life Serial Killers would never have something so blatantly staged as what the three of them find.
- Older Than Feudalism: The Odyssey: Odysseus and his men explore the cave of the cyclops Polyphemus in which they're trapped by his return, knowing it's only a matter of time before he eats them all.
- Dice Funk: The party spends a whole episode searching the underground compound of a villainous faction. Said villain later taunts them for missing important clues while they had the chance.
- Magic: The Gathering devotes an entire set to this trope, appropriately called Stronghold.
- Near the end of Heavy Rain, Madison manages to track down the base of the Origami Killer, and bravely/foolishly breaks into it, hoping to find information about where the kidnapped boy, Shaun, is being held. Whether she succeeds at that or not, the killer surprises her on her way out. She CAN escape with her life - potentially - but if you don't think fast, she will die there.
- And then she does it again in the Downloadable Content episode The Taxidermist; the entire episode consists of breaking into a man's house, finding out he's a serial killer who stuffs women, and then trying to escape when he comes home. Whether she gets out of the house undetected or in a chase (if she does get out at all!) is entirely up to the player.
- Rosella does this in King's Quest IV. Justified in that case, as she does need to grab Genesta's talisman and the magic fruit if she hopes to see Daventry again.
- The entire point of the Dragon's Lair games.
- This is essentially Clock Tower and Haunting Ground in a nutshell, with a little bit of story and a healthy dose of Alone with the Psycho thrown in.
- After the Space Station is destroyed and the baby metroid captured in Super Metroid, Samus goes to explore the now-abandoned Tourian of the Planet Zebes. It doesn't stay abandoned for long, though.
- The end-game of Blackout has such a sequence with the twist being that it is actually the Amnesiac Player Character's own (or rather one of his Split Personalities') evil lair which is being explored.
- The player character and C. Auguste Dupin do this quite often in the Dark Tales series - justified, as this is usually the only way to solve the mystery.
- Subverted in Earthsong, where Willow finds herself in Tristram's lair. She gets up to walk off while he's asleep, and then he calls after her... to note that there are some pretty crystals down that passage there, and, oh, she'd never find her way out.
- Riley and Kalani end up doing this by accident in chapter 23 of We're Alive when they end up finding Ink's Torture Cellar.
- Kaeloo and Mr. Cat wind up doing this in the Season 2 finale in order to find Quack Quack, who has been kidnapped by Olaf.
- Pooh's Grand Adventure features this trope when Pooh and the gang are forced to explore Skull as they seek out Christopher Robin even as this puts them on a collision course with whatever perils might lie in store for them. It doesn't help that they decide to split up, even if it means they cover more ground.
- The Simpsons: In a parody of Alfred Hitchcock's Rear Window, Bart Simpson sent Lisa to investigate the Flanders pad when he thought Ned had killed his wife.
- Star Wars: The Clone Wars: In "Lair of Grievous", Kit Fisto, his former Padawan Nahdar Vebb, and a squad of clones wind up in General Grievous' secret hideout while searching for Nute Gunray. This is all a test arranged by Count Dooku because he thinks Grievous is losing his edge.