Dr. David Krane, Ray Liotta, Seattle's medical examiner, becomes convinced that the same killer who murdered a woman during an apparent drugstore robbery is also responsible for the murder of his wife, Mary Krane, Stellina Rusich, who was pregnant at the time. The case gnaws at him as he seeks connections between the two killings, driven by a need for answers and justice.
Meanwhile, Dr. Martha Briggs, Linda Fiorentino, has created a radical serum that can transfer memories via cerebrospinal fluid. Krane longs to test it, but Briggs is wary of dangerous side effects and refuses to volunteer him for the procedure.
Krane secretly retrieves a CSF sample from Mary’s autopsy and then breaks into Briggs' office. At home, he injects himself with the serum and experiences a fragment of the night of Mary's murder, though the killer’s face remains obscured. He then obtains the CSF from the victim at the drugstore, and with another serum injection, the killer’s face finally comes into view. A police artist helps convert the vision into a likeness.
Briggs confronts Krane about stealing her serum and worries about potential harm to his heart. With the help of his colleague, Curtis Avery, David Paymer, they input the sketch into a computer program. The computer analysis points to a suspect: Eddie Dutton, Kim Coates, a man with a criminal history, including drugs and murders for hire. Avery provides Eddie’s last known address, a motel, and the search intensifies.
There, Krane confronts Eddie and a volatile chase ensues. Eddie grabs a child and raises a knife; Krane wrestles control of Eddie’s gun. Eddie bolts into a church, where he seizes a kid as a hostage. When the police arrive, Detective Don Bresler, Peter Coyote, shoots Eddie dead. Krane’s behavior becomes increasingly erratic, leading to his dismissal from the force, and he later sneaks back into the autopsy room to steal Eddie’s CSF.
Using the serum again, Krane experiences a sexual flash involving Mary. During the vision, he begins to choke Briggs, who administers nitroglycerin and warns that Eddie may not have killed Mary. Krane opens up about his past, admitting he used to drink and that his marriage had been strained for years, and he reveals that Mary was pregnant.
A DNA test on Krane shows the baby is not his. Krane then confronts Mary’s sister, Kelly, Kim Cattrall, who reveals that Mary was having an affair with a detective. The memories sharpen, and Krane suffers a heart attack. In the hospital, another surge ties Mary to a detective, prompting Krane and Briggs to obtain a CSF sample from the detective at a hospice. They debate who should receive the injection, and Krane ultimately restraints Briggs to administer the serum to himself, uncovering that Mary’s affair was with Bodner, a detective, while Bresler’s name surfaces as the corrupt officer behind the earlier case.
As Krane relives these memories, Bresler arrives with a plan to burn them all alive. Kelly arrives at the house with Krane’s kids just as Bresler is about to kill them. Krane defeats Bresler, saving Briggs from the flames, and retrieves the microcassette recorder that captured Bresler’s confession.
Bresler is arrested, but Krane slips into a coma, dreaming of Mary and their children. Dr. Briggs later tells the visiting detective that Krane’s coma stems from his “mental state” rather than his physical condition. In the final dark reflections, Krane looks back and sees Mary fade away, signaling that he has finally let go and may be ready to return to life with his kids.
