Academic scientists Lil Stanhope, Renee Harmon, and Sven Johnsson, Lee James, are pushing the boundaries of immortality by turning their subjects into zombies and storing them in walk-in freezers. Their ambitious project has a clinical edge, and they believe they are on the verge of unlocking life beyond death. Their collaborator Tom Girard, Wolf Muser, refuses further participation and is killed in his house by hooded intruders who inject him with a serum. Ann Girard, Lynne Kocol, Tom's wife, arrives before the intruders can carry away his body.
Detective Kevin McGuire, Thomas McGowan, is assigned to the case, and he believes it ties to the disappearance of medical students Kirk Richard and Bob Russell. Kevin wants to interview Ann—she had dumped him and married Tom the next day—but Lil prevents it. Sven suggests discharging Ann and appointing Cathrin as her home nurse. Cathrin is a zombie. Tom had told Ann about the immortality project, and they attended a ceremony on a beach on Halloween. Tom left to confess to Father O'Brien while Ann watched the students chant “love and immortality” around a bonfire.
At their lab, Lil tells Sven that they are “interfering with nature” and that “the beings we create are not human beings.” Sven reassures her that they will soon unlock the secrets of immortality. Meanwhile, Kevin tells Ann of his suspicions about Sven and Lil. Ann agrees to report back what she finds.
<blockquote>interfering with nature</blockquote>
<blockquote>the beings we create are not human beings</blockquote>
Kevin and Ann interview Father O'Brien. He explains that Tom had said Sven was using curare on rats, reviving them, and keeping them at low temperatures to retard their aging. But after being revived, the rats acted as if they were “almost soulless.” Shortly thereafter, a zombie strangles O'Brien.
Ann gets a phone call from Tom, who complains of feeling cold and numb. The call ends abruptly when intruders burst into Ann's house. She calls Kevin for help and rushes to Cathrin's room, but Cathrin is not there. Instead, a zombie grabs Ann and threatens to kill her and Tom if she continues to cooperate with Kevin. Cathrin returns and denies that anyone was in the house. Not believing her, Kevin takes Ann home, where they sleep together. Kevin declares his love for her; she says nothing about her feelings toward him.
Ann searches Lil's office and discovers photos of the missing med students: Kirk Richard, Bob Rochelle, and Bob Russell, Bill Oliver. She tells Kevin she will search Sven's home lab during his Halloween party. During the party, Cathrin overheats and drops dead.
The party continues. Ann sees Tom staring blankly from the window of an old house. She calls Kevin. She finds a freezer inside the house containing Tom and the missing students, both zombies—the zombies attack. Kevin kills one but is knocked over by a car and taken to the hospital. The second zombie chases Ann. Just as he is about to kill her, Lil appears and tells him that he has been out of the freezer too long. He immediately dies.
Ann is taken to Sven's lab, where he intends to zombify her, but Lil kills him. Lil asks Ann to take Sven's place on the immortality project. As a ruse, Ann agrees but then destroys the lab. An angry Lil injects Ann with the zombie serum. O'Brien, himself a zombie, arrives.
Ann, Lil, and O'Brien visit Kevin in the hospital. Ann, now a zombie, promises that she will love Kevin forever. But her eternal love has a price, which Kevin pays as Lil plunges a hypodermic zombie serum into his eye.
