It sounds like just another urban legend — a videotape filled with nightmarish images leads to a phone call foretelling the viewer’s death in exactly seven days. Newspaper reporter Rachel Keller (Naomi Watts) is skeptical of the story until four teenagers all die mysteriously exactly one week after watching just such a tape. Allowing her investigative curiosity to get the better of her, Rachel tracks down the video and watches it. Now she has just seven days to unravel the mystery.

In Santa Mira, California, Dr. Miles Bennell (Kevin McCarthy) is baffled when all his patients come to him with the same complaint: their loved ones seem to have been replaced by emotionless impostors. Despite others’ dismissive denials, Dr. Bennell, his former girlfriend Becky (Dana Wynter) and his friend Jack (King Donovan) soon discover that the patients’ suspicions are true: an alien species of human duplicates, grown from plant-like pods, is taking over the small town.