On its way back to Earth, the commercial spaceship USCSS "Nostromo" is diverted to a desolate planetoid by a cryptic signal from a derelict alien spacecraft. Inside the alien ship, the crew discovers thousands of egg-like objects. A creature, released from one of the eggs, attaches itself to a crewman's face, rendering him unconscious. The others break quarantine to return him to the "Nostromo". The parasite dies and the crewman wakes up, seemingly unaffected. Soon afterwards, an alien organism bursts from his chest and grows rapidly into a large lethal creature, which the surviving crew attempt to kill. The "Nostromo" is destroyed in an unsuccessful attempt to kill the creature, and Ripley the only survivor in the ship's lifeboat.