Bob Signorelli (Joe Mantegna), a former cop, now works for his friend, Herb as a private investigator. Herb knows that Bob has seen better days, and lately his particular brand of burnout is straining their friendship as well as their working relationship.
When beautiful but troubled Merre (Kelli Maroney) shows up in their office, Bob’s attention is held more by her curves than by her story. It seems she’s convinced she’s being followed by a mysterious sedan and that her apartment has been broken into, though she offers only flimsy evidence for her suspicions. Bob, though completely skeptical, gives an impression of great concern.
Police Lieutenant “Coop” Cooper (Peter Riegert), meanwhile, is investigating the death of a man found in the gutter. Coop has a feud with Signorelli dating back to Bob’s days on the force, when he defied Coop by relying on the word of a questionable informant. Bob even perjured himself to keep his source out of jail. The snitch soon after showed his true colors, killing an eight-year-old girl. Bob was discharged from the force and blacklisted. To this day, Bob is haunted by nightmares and self-loathing; Coop carries a grudge.
As Bob and Merre become romantically involved, he comes to believe she may not be the airhead he first thought. Still, he doesn’t trust her. His suspicions are confirmed when she is present at the fatal shooting of Herb. It becomes apparent that she’s connected with some shady characters -- perhaps even with the corpse found in the gutter. Then she turns up on the cover of a hard-core porno video. When Bob discovers a bottle of lithium, it begins to explain the “many faces” of Merre. She tells him she’s been off the drug for over a month and claims she can’t remember a thing she’s done during that time. Like maybe killing someone? wonders Bob.
Bob’s only remaining avenue of inquiry leads him to Merre’s mysterious boss, Derek Fry (Adam Ant), owner of an art gallery. Merre is convinced Fry helped her by introducing her to lithium in the first place. But Bob suspects Fry has manipulated her by now keeping her off the drug.
In classic film noir style, as this carefully wrought thriller comes to its conclusion, the pieces all fall into place. Or do they?