Stealing liberally from "The Fugitive," "Brainstorm" and even last year's "Strange Days," the new sci-fi/film-noir thriller "Unforgettable" has a fatal problem - it's too easy.

In fact, if you haven't figured out in the first 20 minutes who the bad guy is, turn in your movie-detective badge.

Despite that fatal flaw, and the fact that everything begins to fall apart in the last 10 minutes, the film does boast solid characterizations by a seasoned cast, as well as some inventive direction from John Dahl ("The Last Seduction," "Red Rock West").

Ray Liotta stars as a doctor, specifically a medical examiner for the Seattle police, whose wife was killed a year earlier. Liotta was captured, charged with and tried for her murder - but he got off on a legal technicality and resumed his forensics career. He also lost his kids, who moved in with his sister-in-law (Kim Cattrall).

A former alcoholic, Liotta now drinks mineral water and spends every waking hour trying to figure out who killed his wife, a mystery that has baffled the police detectives on the case (Peter Coyote and Chris-topher McDonald). ("You've seen too many episodes of `Quincy,' " McDonald tells him at one point.)

Liotta stops brooding, however, when he meets a nerdy, divorced scientist (Linda Fiorentino) who has been developing a drug that can be combined with spinal fluid to pull memories from one person and injected into someone else. So far, she's experimented only on rats. But Liotta wants to use the formula to find out who killed his wife.

The good news is, when he steals the drug, mixes it with his late wife's spinal fluid and injects himself, it works! Suddenly he begins reliving the final moments before her death.

The bad news is, she didn't see her killer.

Eventually, he steals spinal fluid from a couple of other people involved in the case, injects himself some more and slowly begins to put it all together. (Much slower than the audience, as it happens.)

Fiorentino, meanwhile, follows him around to watch for side effects. It seems her rats have been dying like flies . . . if you'll pardon the mixed metaphor . . . because the drug weakens the heart, and the trauma of reliving another's "unforgettable" memories brings on heart attacks!

Despite the easy-to-figure mystery, which doesn't even work terribly well as a "why-done-it," much less a "who-done-it," the tension builds fairly well and Liotta and Fiorentino's characters are sympathetic enough to carry us along.

Director Dahl's use of the re-created memories from various viewpoints is cleverly devised, and there's a terrific foot-chase through town about halfway through the picture. And the performances are uniformly excellent, including Fiorentino, who is cast against type as a woman who is anything but the femme fatale that has recently made her an above-the-title player.

But the film too often goes in for gruesome theatrics, with violence in some scenes repeated a few too many times. And the script, by first-timer Bill Geddie, is filled with lapses in logic and needs a strong sense-of-humor injection.

"Unforgettable" is rated R for violence, some blood and gore, a few strong profanities, nudity (dead bodies in the morgue) and drug abuse (a villain snorting what is probably cocaine).