Ripley is introduced as a warrant officer aboard the Nostromo, a spaceship en route to Earth from Thedus. Following their landing, an unknown creature infiltrates the ship, and kills every other member of the crew. Ripley is the only member to escape from the Nostromo prior to its explosion. 57 years later, Ripley awakes from her stasis. They find the planet infested by many Aliens, who wipe out almost all of the marines. Ripley finally escapes the planet with a few survivors.