Het derde hoofdstuk van een van de meest spannende Science Fiction films ooit gemaakt. Met in de hoofdrol natuurlijk weer Sigourney Weaver. In de rold van Lt. Ripley stort ze neer op de zwaarbewaakte planeet Fiorina 161, waar de meest gevreesde criminelen van het universum gevangen zitten. Helaas was Ripley niet de enige passagier in het ruimteschip. Wederom gaat Ripley de strijd aan met het monster.
The film begins on board an escape vessel in which Ripley, Newt, Hicks, and a droid called Bishop are traveling on. The pod crashes on a planet inhabited by prisoners who have been left to govern themselves in a facility, killing Newt, Hicks, and destroying Bishop. Ripley is revived from her cryo-sleep from the prison doctor and soon discovers what happened to her and her remaining crew members. After calling for assistance from the Company they wait for Ripley to be transported off the planet, as she doesn't belong there. After a short time, a shaven-headed Ripley starts discovering that prisoners are being killed in a very similar manner to that of the Aliens she has faced in the previous two films. Once this is discovered, she and the remaining prisoners must devise a plan to kill the Alien that stalks the prison facility, hiding in ventilation shafts. However, she soon discovers that that it isn't the only Alien on the planet. There is also a Queen, but where?
