An alien from a race dying of a disease crashes on Earth and assumes the body of a human. She then precedes to take blood from other humans to send back to her planet. Things get complicated when she starts to feel human emotions and other aliens show up to exterminate her. Her only hope lies with a curious and helpful doctor.

Seven years ago, Regina (Mimi Rogers) was tried for the death. On the night before she becomes the first woman in over 40 years to be executed in a federal penitentiary, she befriends the lone, curious prison guard Colin Reeves (Billy Zane), who has been assigned to watch over her. By telling Regina's story through flashbacks interwoven with her present situation, the film helps us understand this woman in a unique, disturbing and sympathetic way