Criminal psychologist Helen Hudson (Sigourney Weaver) is an expert on serial killers. She's gotten so close to unlocking the psyches of her previous subjects that one -- an incurable psychotic (Harry Connick Jr.) -- almost murdered her. Now she's an agoraphobic, living a terrified existence defined by the walls of her apartment, with her computer modem and her loyal and compassionate assistant, Andy (John Rothman), her only links to the outside world. She waits in terror for the day she'll hear the voice of her stalker again.
Smart, ambitious police detective M.J. Monahan (Holly Hunter) is determined to stop a new siege of murders in San Francisco and she needs Hudson to find the perpetrator. A driven pursuer, Monahan, assisted by her young partner, Ruben Getz (Dermot Mulroney), will do whatever it takes to enlist Hudson's help. The two women find themselves locked in a struggle of wills as Hudson tries to remain uninvolved and Monahan is determined to end the doctor's self-imposed exile. And the murders keep occurring, taking on an ominous pattern that only Hudson can recognize... But now their quarry discovers he's being monitored, and he figures out who's doing the observing. Helen Hudson knows how he thinks.