Plot

A mentally disturbed woman is further tormented after discovering a girl who closely resembles her recently deceased daughter.

Gina (Melissa Gilbert) has recently lost a very young daughter and is haunted by her memory. Recently out of the psychiatric hospital, she works for clothing store owner Nikos Lassandros (Thaao Penghlis) trying to put her life back together.

But when she spots a woman bearing an eerie resemblance to her deceased child, Gina's new life quickly begins to unravel. She sees only a brief, fleeting glimpse of this woman, making her believe she was just hallucinating. Nikos, a believer in various myths, thinks that this is a doppleganger-- a creature capable of looking like a person, and who tries to replace that person to live their life.

Gina's mother, Mary Helen (Diane Ladd) and psychiatrist, Dr. Stamos (Frances Lee McCain), try to counsel and comfort Gina, but can do little to soothe her troubled mind. Dr. Stamos wants to do a hypnotic regression session with Gina to dig for what she is sure are long-buried memories, but Gina is relucant-- and frightened. Gina sees further glimpses of this strange woman and comes to strongly believe in the doppleganger story-- and starts to come unhinged when Nikos says that Gina's seen signs that indicate that the doppleganger is preparing to make contact with her-- a first step in taking over her life and replacing her with itself.

The situation comes to a head when Nikos unveils a mannequin in his shop window that looks exactly like Gina. Gina is walking through the mall in which the store is located when she finally comes face to face with the mysterious woman. Thinking the doppleganger is about to strike, Gina turns and runs off in terror, and we see the lookalike mouth the word, 'Wait!' before happening to pass by Nikos' store. She walks up to the window where the mannequin is displayed and stares at it in amazement. Nikos sees the woman-- something that should not be possible if she were a doppleganger, as only the intended victim of a doppleganger can see it-- and rushes out of the store after her.

Gina is with Dr. Stamos, and tearfully begs to be placed back in the hospital. Before the psychiatrist can start questioning her about it, Nikos arrives in the office with the lookalike. Gina recoils in terror, until Nikos assures her that the woman is real... flesh and blood... and claiming to be her twin sister, Jennifer (also played by Melissa Gilbert).

Gina undergoes the hypnotic regression therapy with Dr. Stamos while Nikos and Jenny wait outside the office. During the session, long-buried memories come to the surface... she was with Jenny and their mother while she and Jenny were very young children, driving down a road in a pouring rainstorm, when in a freak accident, as they were crossing a bridge over a river, Gina fell out of the car and was swept off by the rains. It comes to light that Mary Helen is not, in fact, Gina's mother... Gina realizes Mary Helen found her on the banks of the river and took her for her own.

Gina steps outside the office where Nikos and Jenny are waiting. Gina finally remembers Jenny, and understands that she is her sister, and the two of them share a joyful reunion embrace. The two of them are driving to Mary Helen's home to confront her. Gina still defends Mary Helen's saving her life, but Jenny is firm in a belief that the woman kidnapped her.

During the confrontation with Mary Helen, Gina's memory finally becomes complete... she realizes that, hearing the young Gina call out 'Mommy' repeatedly when Mary Helen found her on the river bank, Mary Helen became consumed by a need to fill the role--- and killed Gina's real mother, who had come running in search of her. Something inside Mary Helen snaps and she lifts a heavy object, seemingly to kill Gina-- but Jenny intervenes, and Gina pulls the object away.

The movie closes with Mary Helen locked away in a mental institution, and Gina reaching some happy stability, finally having put the pieces of her life back together... and happily reunited with her sister.