静静的宇宙,一艘名叫“贝蒂”的太空船正在飞向“御夫座”星球。船上躺着数十个被麻醉冻僵了的地球人,他们全然不知即将到来的灾难。原来,丧尽天良的军方和商人将这些人诱拐过来,要送到“御夫座”上孵化异形女皇两百年前生下的蛋。 雷普莉(西格妮•韦弗 Sigourney Weaver 饰)已成为了异形女皇生下的转世为人的异形人。她的基因里带上了异形的基因,变得特别强壮、忽明忽暗,成了“双面人”。“贝蒂”上有个叫考尔(维诺娜•赖德 Winona Ryder 饰)的年轻女人,正在设法破坏孵化异形蛋计划。当“贝蒂”来到“御夫座”,意想不到的情形发生了!200 years after the conclusion of Alien 3, the Company is able to resurrect Ripley through the process of cloning and the scientists successfully take the Queen Alien out of her. But, Ripley's DNA gets mixed up with the Queen's and she begins to develop certain alien characteristics. The scientists begin breeding the aliens, but they later escape. Soon the Xeno-morphs are running amok on the ship, which is on course to Earth. The Queen then gives birth to a deadly new breed of alien, which could spell disaster for the entire human race. It's up to Ripley and a band of space pirates to stop the ship before it reaches Earth.