A basic, now classic, horror plot which follows the simple formula: Some characters are stuck in a partly constricted space, such as a building or large vehicle of some sort, while menaced by some threat, usually some vicious creature that is hunting them. The cast avoids the threat to the best of their ability while trying to concoct a method of resistance; if initially more than a few people, their number dwindles as they are devoured or otherwise disposed of one after another, until such time as the monster is defeated or they manage to engineer an escape. The essence of the trope is the immediacy of the conflict between characters and their predator, who have no chance to flee or withdraw to form an ideal plan of attack; with every moment, the risk of an encounter is mounting.
Circumstances ensure that the characters can't simply leave: if they're in a structure, it will be somehow isolated or surrounded by a hazard. The most common choices are a space station or, similarly, an underwater habitat. A vehicle will usually be something equally enclosed and inescapable, like a plane, submarine, boat, spaceship. If a land vehicle, it will have to be traveling through an inhospitable area, like a desert. The area to be at least moderate in size to ensure some kind of story can happen, so a single room or a car won't work; but similarly, the space can't be so large that the prey can just keep running away.
The isolation creates an environment with a lot of potential. There are cubbies, alcoves, and storage areas to hide in; corridors to run through; air vents to sneak through; open, communal areas that create the illusion of safety. There is also maintenance equipment that can be used as an Improvised Weapon; devices and instruments that can be reconfigured as traps. Any of these can be used by the protagonists or the creature in their perpetual game of cat-and-mouse.
The use of a vehicle adds further complications. If operational, is imposes a time limit on the story, as it will (hypothetically) eventually carry everyone to safety; thus, the protagonists in principle need only survive long enough for it to arrive. It not operational, getting it running will be the major goal for at least the first act. This, in turn, creates an extra level of threat, as the monster can, if unable to reach the protagonists, still screw them over by wrecking their transportation.
Compare Shark Pool and Fed to the Beast, where the villain intentionally puts the hero in a confined space with a monster. Often coincides with Exploring the Evil Lair. Contrast Alone with the Psycho.
- Played with in the "Homeschooling" arc of Runaways, in which an accident causes Klara to trap her teammates inside their Malibu house. Victor grows increasingly convinced that Klara's powers are a danger to them all, but it later turns out that she's actually protecting the team from a paramilitary group that has shown up to investigate and "contain" the accident (i.e. kill all witnesses and destroy all the evidence.)
- In Alien, a highly ferocious extraterrestrial menaces the crew of a freighter spaceship. It is, though not the Trope Codifier, one of the most famous examples in sci-fi. As such, many subsequent sci-fi works following this trope are homages. Almost all of its many sequels, tie-ins, and crossovers have followed the same format.
- In Horror Express people are trapped on the Trans-Siberian Express train with a prehistoric monster which was found frozen in ice but has thawed out.
- The premise of John Carpenter's The Thing is that a polymorphic alien crashed on Earth during the Ice Age, and has been in suspended animation in Antarctica until some Norwegian researchers discovered it. The alien wiped out their compound and fled to the American base disguised as a sled dog. Given enough time, the alien can mimic any organism it consumes, and the American researchers have nowhere to flee that isn't sub-zero cold.
- The researchers on Saturn3 see a shuttlecraft / supply ship once every six months. When obsessive psychopath Benson joins them and builds a mind-linked super-robot, the robot downloads Benson's psychoses and begins lusting after nubile Alex. Retreat becomes impossible when the robot destroys the only launch capable craft on their moon.
- Fer-de-Lance is a 1974 TV movie about a submarine trapped on the ocean floor with escaped poisonous snakes running loose.
- It's a slightly larger space, but Tremors has a similar plot. The residents of a small desert town are menaced by giant SandWorms, and must try to survive. They can't easily leave because there is only one road out of town and it has been blocked by the worms and attempting to leave on foot would be suicide.
- Tremors 2: Aftershocks: Same deal as the first film, but this time the group of humans have to deal with the smaller, more numerous, bipedal offshoot of the Graboids, which they dub "Shriekers" on account of the sound they make. While it doesn't hunt based on sound (being both blind and deaf), it can detect any heat signature, which also causes them to attack all machinery including car engines, disabling it, and trying to run from them in a wide open space is similarly suicidal.
- Tremors 6: A Cold Day in Hell: The group is stuck at the facility with no cars or high-power weaponry. They're also situated in a geographically isolated valley with mountains on all sides, which gets a Lampshade Hanging from Burt. He further notes that it's only a matter of time before a Graboid starts smashing through the floorboards to get them.
- The Abyss has a twist — the crew of an experimental seafloor habitat encounter aliens, but these turn out to be benign (ish), and one of their own members is the real threat.
- Event Horizon: An experimental hyperdrive goes horribly wrong.
- Snakes on a Plane is basically this trope played up to the most troperiffic possible level.
- Predators features a group of hardened mercenaries and murderers, general scum of the earth, sent offworld to the hunting grounds of a single Predator who systematically hunts them down.
- In Bait 3D, a group of people are trapped in a partially submerged convenience store with two great white sharks after a tsunami devastates the coastal town.
- In Deep Blue Sea, a group of scientists are trapped inside an underwater research laboratory with three genetically enhanced sharks. It also happens over the weekend, meaning that most of the facility's personel is on leave, leaving only a skeleton crew of about 10 people to deal with the sharks.
- In The Ruins, the film's major plot twist is that the backpacking group on the Mayan temple are trapped there because the ruins are covered with a supernatural, hyperintelligent plant-like monster with a craving for human blood.
- Most of Deep Rising takes place on a stalled cruise ship. Although the protagonists do have a boat of their own, its engines are damaged in a collision early on, so it won't be able to take them to safety unless they can retrieve replacement parts from the tentacle-infested cruise ship's machine shop.
- It! The Terror from Beyond Space has various astronauts trapped with a blood-sucking Nigh Invulnerable Martian inside of a rocket that is in the middle of its four-month journey back to Earth from Mars. Essentially a prototypical Alien made in The '50s (and not really that odd—it was one of Dan O'Bannon's favorite films).
- Train to Busan has an increasingly-dwindling number of humans trapped with an increasingly-growing horde of zombies on a train en route to a safe zone.
- A Quiet Place: The mother is trapped with one of the monsters in the house a couple of times and is forced to be incredibly quiet lest the creature's powerful hearing picks up on her. The kicker? The first time, she's on the verge of giving birth.
- Charlie and the Great Glass Elevator has a major portion devoted to Charlie et al. visiting a Space Hilton that has been taken over by vermicious knids. In this case, because they came in the titular elevator they are able to just leave again, though it's a narrow escape.
- Life of Pi: Kid trapped in a lifeboat with a tiger.
- In Ciaphas Cain: The Emperor's Finest, Cain ends up trapped aboard a space hulk after getting separated from his Space Marine companions by a tyranid attack (note: the tyranids are based in part on the xenomorphs from Alien), and spends the rest of the book having to evade both them and a party of orks that are also aboard. Then he has the bright idea to trick them into fighting each other, making the Space Marines' job a heck of a lot easier after he gets back to them.
- The Goosebumps book How to Kill a Monster is about a brother and sister who are sent off to live with their backwoods relatives in the countryside for a while. Then their caretakers take an unannounced trip to town when they discover that a swamp monster was sleeping in the basement, which they accidentally woke up.
- Doctor Who uses this often, frequently with reference to Alien. Because the principal narrative device in the series is the TARDIS, which is literally as big inside as the writers want it to be, an easy episode to write is "some monster invades the TARDIS and everyone has to flee it until the Doctor figures out how to defeat it." New series examples include:
- "42": One of a space freighter's crew is possessed by a sentient star and becomes bent on spreading its influence to the rest. A subplot concerns trying to reach and repair the main engine to get away from said star before the ship falls into it.
- "Midnight": In an interesting twist, the vehicle is only the size of a small room, with rescue on the way, but the monster hunts the characters through labyrinths that are psychological rather than physical: it takes them over by repeating their words, in a process that is never entirely explained.
- "The Curse of the Black Spot": The crew of a becalmed pirate ship is hunted by a siren who targets anyone with an injury or health deficiency.
- "The Doctor's Wife" has a moment of this, when House takes over the TARDIS and sends Amy and Rory scurrying around the corridors. Mostly he plays with their heads in an Interface Screw type of way, but he also sends his pet Ood, Nephew, after them to finish them off.
- "The God Complex" A spaceship/prison traps people in what seems like an infinitely recursive hotel while a minotaur chases them down.
- "Cold War": A Martian Ice Warrior is discovered and thawed by a Soviet nuclear submarine during the '80's. It spends a lot of time hiding in air vents and Neck Lifting people, and the rest of the time trying to fire the sub's missiles in a deliberate gambit to start a nuclear war.
- "Journey to the Centre of the TARDIS": What starts as a search for Clara, who has gotten lost somewhere in the bowels of a damaged TARDIS, becomes a flight from a handful of burnt zombie-creatures.
- "Mummy on the Orient Express": A train, reconstructed for space travel, harbors a mummy-like creature called the Foretold that drains the life from its victims one at a time.
- In the Stargate SG-1 episode "The Tomb", SG-1 and a prototype SG team from the Russian Air Force get trapped in the tomb of the Goa'uld System Lord Marduk, and it turns out there's a critter of some kind in there with them that starts attacking them. It turns out to be a critter that Marduk's priests entombed with his sarcophagus to slowly kill him, but the symbiote jumped hosts to it.
- The Star Trek: Deep Space Nine episode "Empok Nor" has a squad from Deep Space 9 trapped aboard its sister station Empok Nor by a unit of Cardassian black ops soldiers left behind in stasis as a booby trap. There's also a gas in the air that causes Cardassians to become violently xenophobic, which makes Garak take over as the monster after he kills the last soldier.
- Wizards of Waverly Place: In "Night at the Lazerama", Justin and Juliet go hunting for a mummy in the museum and get trapped there when it closes for the day. Since looking into the mummy's gaze will make one his mind slave, Justin suggests they try to avoid him until morning, which is bad news for his vampire girlfriend. In the end, Juliet willingly stares at the mummy to save Justin.
- In MOTHER 3, there is a segment in which your party is locked inside a chimera research lab. It's not long before the experiments start getting uncaged, including the lab's magnum opus, the Ultimate Chimera. It's not exactly friendly.
- Alien: Isolation is a Survival Horror game in the Alien franchise with the player character trapped aboard a space station with a xenomorph that killed the entire crew.
- Five Nights at Freddy's and its sequel downplay this; you're stuck in a building full of murderous animatronics, but you're willingly in there for a (minimum wage) paycheck. The sixth night of the sequel, though, does this more literally: you missed a memo and weren't supposed to be at the building that night. You're then encouraged to stay there and hold out until the robots shut off at 6 am, rather than try to escape out of there in the dark.
- Until Dawn traps the eight protagonists with the Wendigo on a frozen mountaintop, in the snowstorm, with the only way down being a cable car that's been moved too far away from the station for them to be able to jump to it, and the key that would activate the cable car missing.