aliens

The Nostromo tug spacecraft is on its return journey from Thedus to Earth, towing a refinery and 20 million tons of ore, carrying seven crew members in cryosol. Upon receiving a transmission of unknown origin from a neighboring planetoid, the ship's computer wakes up the crew. Acting on orders from their employers, the crew detaches the Nostromo from the refinery and crash-lands on the planet, damaging the ship. Captain Dallas, First Officer Kane and Navigator Lambert leave to investigate the source of the signal, while Warrant Officer Ripley, Science Officer Ash and Engineers Brett and Parker stay behind to monitor their progress and repair the ship.Dallas, Kane and Lambert discover that the signal is coming from an abandoned alien ship. Inside they find the remains of an enormous alien creature whose ribs appear to have exploded from the inside out. Meanwhile, the Nostromo's computer partially deciphers the broadcast signal, which Ripley determines to be some sort of alert. Kane discovers a large chamber containing several eggs, one of which launches a maniform, which attaches to his face. Dallas and Lambert carry Kane to the Nostromo. Ash allows them to enter against Ripley's orders to follow the ship's quarantine protocol. Unsuccessfully, they attempt to remove the Maniform from Kane's face, discovering his blood to be an extremely corrosive acid. Eventually, the Maniform breaks free on its own and dies. With the ship repaired, the crew continues their journey back to Earth.Kane wakes up, apparently unharmed, however, during a meal, before they go back to the cryogenics pods, he starts choking and having convulsions until an alien creature comes out of his chest, killing him and fleeing through the ship. With no conventional weapons, the crew tries to locate and capture the creature by creating motion sensors, electric prods and flamethrowers. Brett follows the crew's cat into a large room where the now-grown Alien attacks him and disappears with his body through the ventilation system. Dallas enters the ventilation system trying to force the Alien into an airlock where he can be expelled from the ship, but he is ambushed by the creature. Lambert begs the rest of the crew to escape on the Nostromo's shuttle, but Ripley, now in command, explains that the shuttle will not support four people.

Accessing the ship's computer, Ripley discovers that Ash has been ordered to bring the Alien to Nostromo's employers, even at the cost of the entire crew's lives. Ash attacks her, but Packer intervenes and cuts her head off with the flamethrower, revealing that Ash was an android. Before Parker incinerates him, Ash predicts that the rest of the crew will not survive. The three remaining people plan to activate the Nostromo's self-destruct sequence and escape via the shuttle, but Parker and Lambert are killed by the Alien as they gather the necessary supplies. Ripley initiates the self-destruct sequence and goes to the shuttle with the crew's cat, but the Alien blocks her path. She unsuccessfully attempts to abort the self-destruct sequence. Ripley returns and finds the Alien gone, escaping at the last minute from the Nostromo's explosion.
As she prepares to go into hypersleep, Ripley discovers that the Alien is aboard the shuttle. She puts on a spacesuit and opens the hatch, causing an explosive decompression that forces the Alien out through the open hatch. She shoots with a grappling hook weapon, but the weapon leaves her hand and gets stuck in the door, tying the Alien to the ship. The creature tries to go to one of the engines, but Ripley activates them and the Alien is expelled into space. She then enters the cryogenics pod along with the cat, continuing her journey back to Earth.