"Exposed," a poorly resolved but seductively intriguing mystery thriller, brings about the effective collaboration of the slightly notorious writer-director James Toback ("The Gambler," "Fingers," "Love and Money") and Nastassia Kinski. Always a fascinating camera subject, Kinski reveals herself in this film as a potentially exciting, affecting and remarkable young actress. You can watch this transition occur.

Toback has been clever enough to contrive a mutual liberation vehicle for himself and his beautiful young star. The heroine, Elizabeth Carlson, is a romantically susceptible but also intelligent American coed, drawn into international political intrigue after she drops out of college and achieves whirlwind success as a fashion model in New York.

This role gives Kinski the opportunity to humanize her extraordinary beauty by embodying a fundamentally decent young woman whose own head is not turned by the fame she suddenly enjoys. The events of the story are calculated to shock, bereave and haunt her but not to leave her looking at all coarsened, emotionally or morally.

This bedrock integrity in the heroine comes as something of a surprise. The cliche's of the genre lead one to anticipate a moth-to-the-flame character, a girl whose boredom with a secure, conventional existence lures her into self-destructive behavior. Toback skirts this expected trap, perhaps to his misfortune in the long run, since the plot seems to fizzle down the stretch when Elizabeth becomes a helplessly innocent, ineffectual witness to episodes of treachery and violence.

Nevertheless, the movie imposes a suspenseful hold because it's got an unpredictable momentum. You feel pulled along right at the outset--in a scene depicting the bombing of a Parisian restaurant by a group of terrorists who will remain shadowy until the last act--and surprised by many twists and turns.

Although he falters at the denouement, Toback has never shown such effective, rhythmically absorbing technique before, and it should help to bring him at least to the verge of mainstream acceptance.

However, the key innovation on Toback's part is his invention of a leading character who cannot be immediately confused with his own ambivalent self-image. He has begun to free himself from a chronic dependence on obvious masculine alter-egos in the act of creating a role that also begins to free Kinski from the beauty trap.

Toback showed considerable directing skill in "Fingers," but this first feature was messed up emotionally by his inability as a screenwriter to provide points of entry into the turbulent mental processes of an obsessive, semi-autobiographical protagonist. This stumbling block appeared in Toback's first screenplay, "The Gambler," and evidently he was unable to remove it before being inspired to write a movie for Kinski.

The borderline crazy behavior that Toback seemed drawn to--maybe even took for granted--wasn't necessarily comprehensible or sympathetic to spectators. He assumed an affinity for types "who want to live on the edge of annihilation." This new movie may prove both an expressive and commercial breakthrough for Toback because it reveals him identifying with a character who's lured to the edge without going over it.

Elizabeth doesn't perceive anything exhilarating or fulfilling when invited to peer over the edge, at least as it's understood in masculine literary terms, and flirt with criminality and death. It's love that draws her into a deadly situation, but she displays no death wish. Indeed, she's the first Toback protagonist who seems essentially sane.

"Exposed" is full of haunting and amusing echoes of The New Wave, and it's been photographed in sumptuous color by one of the men who helped create and sustain that filmmaking movement, the great Henri Decae.

Toback's apparent rapport with Kinski results in some extraordinary moments, notably a sequence in which Elizabeth is alone in her apartment and works off nervous energy by going into a spontaneous dance that turns into an erotic sensation. Toback himself appears in the most effective comic role in the film, as the pompous, naggy English professor whose possessiveness is one of the heroine's best reasons for quitting college. There are some obligatory bits that seem to elude the director and star, including an absolutely essential reaction shot in the scene in which Elizabeth witnesses a coldblooded murder, but for the most part Toback and Kinski seem to do wonders for each other.

The wonders tend to cease with the other leading roles. Toback's writing inclines toward the schematic in ways that place a heavy burden of proof on his casting--and leave a narrow margin for error, of course. The actors need to embody their characters more or less on sight, because the material may not be sufficient to make sense of them.

As Elizabeth's devious, dangerous suitors, both Rudolf Nureyev and Harvey Keitel fail to rationalize such shaky assignments, and Toback inflicts Keitel with a long, self-analytical confession that strains credulity even further. Nureyev is the far more novel and diverting piece of miscasting, and he's also hilariously instrumental to Toback's kitschiest transports of romance, which add an absurd ersatz glamor to the movie.

It would be misleading to pretend that "Exposed" is a totally satisfying romantic thriller. It demonstrably isn't everything Toback wants it to be, including a romantic thriller of provocative ideas. Still, its miscalculated ideas tend to release more energy than one finds in conventional thrillers, and the excitement generated by Kinski at her most appealing, as well as sexy, justifies a larger ration of tolerance than "Exposed" really needs. EXPOSED

Directed, written and produced by James Toback; director of photography, Henri Decae; production designer, Brian Eatwell; edited by Robert Lawrence; music composed and conducted by Georges Delerue; executive producer, Serge Silberman. A James Toback Film, released by MGM/UA Entertainment Co. This film runs 99 minutes and is rated R. THE CAST Elizabeth Carlson . . . . Nastassia Kinski Daniel Jellin . . . . Rudolf Nureyev Rivas . . . . Harvey Keitel Greg Miller . . . . Ian McShane Margaret . . . . Bibi Andersson