THE FASCINATION with the woman who is hopelessly damned often defies explanation, but the reality of the reaction is difficult to brush off easily. In some ways, this kind of response to witnessing a woman consume herself parallels the perverse motives that drive her to the sordid end; the observer and the observed find themselves drawn into a seance of self-debasement, the former deriving a twisted pleasure from watching the ritual of her decline and fall, the latter from the mere act itself.

Comparing this experience with the compulsive sensation of gawking at a traffic accident fails to capture the essence of the phenomenon under study here. On the one hand, you are dealing with a mass of tangled metal marking the deaths of otherwise unknown people, while on the other hand you become personally involved with the drawn-out spectacle of a human being operating on an auto-destruct frequency. You find yourself reduced to the conclusion that the ingredient of empathy has come into play at some point during the vigil, even if the precise reasons accounting for your continued presence persist in eluding you.

Judith Rossner, the author of Looking for Mr. Goodbar, clearly understood the appeal of this kind of masochistic allegory, as the best-seller success that greeted her pulp novel demonstrated. That Richard (In Cold Blood) Brooks-should decide to bring this trash-posing-as-fiction to the screen also shows at once a keen eye for the commercial and a readiness to pursue his art within the constraining framework of a depressing narrative. In taking on a character like Theresa Dunn as the focal point of his film, Brooks has confirmed an affinity for the dark underside of the individual initially suggested by his adaptation of Truman Capote's book on the massacre of a Kansas farm family. Such subject matter arouses doubts as to the director's artistic aspirations, if any.

Casting Diane Keaton in the role of Dunn has proved to be a wise move by Brooks. Her past appearances in various Woody Allen films have left American audiences with a very tangible image of the actress: an often capricious yet charming woman who generally musters the strength to resist the prodigal nebbish's amorous advances. Keaton has tackled a character in Looking for Mr. Goodbar who is virtually an antithesis of her previous roles. Her Theresa Dunn is a willing woman, to put it charitably, a closet nympho who repeatedly allows herself to be sacrificed to the discredited altar of machismo. Although the context in which she finds herself working is an unfamiliar one, Keaton delivers a flawless performance in her first leading role in a serious drama. The frustration and aimlessness of the Dunn character comes off in convincing fashion, and Keaton never shows any sign of shying away from portraying the depths to which her single schoolteacher descends.

True to the two-sided nature of the leading character, Looking for Mr. Goodbar has a schizoid quality all its own. The first half of the movie eclipses the ensuing 60 minutes in restraint and insight: indeed. Brooks fleshes out Dunn so well that he cannot avoid the unfortunate fate of his concluding scenes smacking of an anticlimax. The film initially focuses on a compelling dynamic at work in the psyche of Dunn, a wrenching struggle between two seperate identities that cannot be accommodated within the fragile limits of her unstable emotions.

Reflecting her feverishly Catholic upbringing, Theresa feels a strong humanist obligation that is met by her line of work, teaching deaf children in a New York elementary school. She singles out a black girl in the class named Amy to concentrate her care and affection on, a trying task that is compounded by the stand-offish attitude of Amy's hate-filled older brother. The scenes showing Theresa striving to win over Amy's trust number among the more poignant encounters in the film, giving the viewer a taste of Dunn's better side. But the effect is quickly and skillfully erased when the camera shifts from her classroom to the sleazy Manhatten bars Dunn frequents each night in search of the pick-up, and Brooks cleverly alternates between these two settings throughout the length of the first hour.

Regrettably, the director largely abandons the altruistic thread in the narrative as he increasingly dwells on Dunn's plunge into the hedonist ethic. The repeated humiliation accorded Theresa by her handsome sexual swordsman (Richard Gere) is designed to serve as a counterpoint to the unrequited love showered on her by the enraptured James Morrissey (William Atherton), but the novelty of the contrast quickly wears off as the subjugation of Theresa becomes progressively uglier. She throws herself into cocaine-sniffing, prostituting herself for the thrill of the act, and blowing off Morrissey out of sheer spite. The schoolteacher identity is tossed away in the process, and while the plot occasionally returns to the classroom setting for a change of pace, the movie ultimately degenerates into an orgiastic display of violence and wanton sex that approaches the Dornographic.

Looking for Mr. Goodbar is very much an American movie. Opening with a montage of black-and-white stills of Theresa, the film relies heavily on crisp quips to furnish some badly needed levity to the story, and Brooks is not averse to using quick cutting from scene to scene to keep the action moving. One-liners like "Confession is good for the soul but it's bad for sex" are supposed to pass for slick dialogue, and they do succeed in eliciting the nervous chuckles, but the script seems to have been written with no higher purpose in mind than to keep the audience reasonably titillated. By devoting his energies to giving the film as glossy a sheen as possible, Brooks never explores the broader implications of the Dunn character, such as thorough discussion of how prominently Dunn's religious background figures in the chemistry of her personality, an unfortunate omission in light of the film's generally mindless quality.

Brooks altered the structure of Rossner's novel in only one instance--by placing the murder at the end of the movie instead of at the beginning--and the film on balance suffers as a result. The director undoubtedly made this change for a specific reason; by saving the murder of Theresa until the final scene, Brooks was able to exploit the effective technique of timing a flashing strobe light in her bedroom with the rapidly mounting and then slowing heartbeat of the victim. In so doing, however, Brooks traps himself in to the quandary of suddenly thrusting the murderer into the narrative without any kind of introduction. A vagrant cowboy type appears out of nowhere, picks up Theresa at Goodbar's and slays her--all within the brief span of a few minutes, asking the viewer to bite off far more than he can be expected to chew. All of which suggests a film that the director suddenly became bored with, a feeling that most audiences of Looking for Mr. Goodbar will find very easy to share.