Undated (AP) _ In their publicity material for the movie ''Presumed Innocent,'' Warner Bros. asks reviewers not to reveal the ending or say whether Rusty Sabich (Harrison Ford) is innocent or guilty.

It's an interesting request, considering that the 1987 Scott Turow best- selling novel sold more than 1 million in hardback and millions more in paperback. Needless to say, a lot of people know Rusty's fate.

But nothing that happens at the beginning of the Alan J. Pakula courtroom thriller, or even as it unravels, sets up the end. The movie is plump with twists, turns and blind alleys. Who can be trusted? Who is innocent? Who is guilty?

The novel is set in mythical Kindle County, in an unidentified Midwest city with Chicago-style politics and corruption. The movie was shot in Detroit.

Rusty, a married, top-flight prosecutor, is assigned to investigate the murder of another prosecutor, Caroline Polhemus (Greta Scacchi), with whom he had been sexually involved. Polhemus was found bludgeoned to death and tied up in what appeared to be an act of sexual bondage.

But a glass containing a little beer and Rusty's fingerprint is left in plain view, making it real easy for police to point a finger. A telephone check also finds numerous calls made from Caroline's number to Rusty's number and vice versa, including a call made the day of the murder.

Rusty wasn't the only man bedding Caroline. His boss, Raymond Horgan, the chief prosecuting attorney, also was intimate with Polhemus. Horgan is in the midst of a bitter campaign for his seat against the smarmy Nico Della Guardia. Horgan (Brian Dennehy) loses the election and serves up Rusty - on a platter once he discovers Rusty's relationship to Caroline - to his former foe.

Rusty hires the best defense lawyer around, the scholarly and elegant Sandy Stern (Raul Julia), and the game is afoot.

Woven into the courtroom suspense is a thread of corruption that goes back to Polhemus' days as a probation officer and somehow involves Della Guardia's sidekick, a moldy little prosecutor named Tommy Molto (Joe Grifasi).

The strength of ''Presumed Innocent'' is its rich gallery of well-developed characters. Its weakness is perhaps in execution of the final plot turn. The book crafts duplicity and surprises far better than the almost labored denouement presented on film. And a key clue, one the camera sweeps by in a flash, and pivotal to knowing who the murderer is, never really blossoms.

Caroline Polhemus is a nasty piece of work, disliked by men because she's aggressive and beats them at their own game. She volunteers to tackle sex crimes, cases usually relegated to the worst lawyers in the department because they're a no-win situation.

However, it is unfortunate that the author and now the filmmakers seem to think that the only way a smart woman can succeed professionally is by sleeping her way to the top.

Polhemus is sexually attracted to Rusty because he represents power in her office and is just a step away from the No. 1 spot, a spot she covets. But why is Rusty drawn to her? There is no chemistry or sexual tension between them. But he falls into her arms after a tough child abuse trial like a lovesick puppy.

Ford plays Rusty straight, almost too straight. He loves his wife, we surmise and is happily married, we suppose. Or, is he bored by a wife who whines about being a housewife and mother?

He admits he does not love Caroline but she's gotten into his blood. Or, perhaps just the passion and lust have. Theirs is a purely sexual bond. Still, his motive for engaging in a professionally and personally dangerous affair is fuzzy.

Scacchi, a European beauty, is seductive and hungry as Caroline. She can be an ice queen, but has a gentler side as when she coaxes an abused child into testifying against his mother.

As Rusty's wife, Barbara, Bonnie Bedelia radiates compassion, frustration, love and fear. It is one her strongest performances.

Julia puts in a good turn as Sandy Stern, and Paul Winfield adds charm and humor to courtroom prancing as the trial judge, Larren Lyttle. There's also good support from Brian Dennehy as Raymond Horgan and John Spencer as the hard-working detective whose loyalty and sense of duty figure importantly in the end.

Pakula (''All the President's Men,'' ''Sophie's Choice'') takes his time unraveling the story from the screenplay written by himself and Frank Pierson (''Dog Day Afternoon''). He plays for reactions, underlying motives, the quirky human element.

And here, he has a great similarity to Otto Preminger's handling of courtroom suspense in 1959's ''Anatomy of a Murder'' with James Stewart. But missing is the hard-edged tension Billy Wilder sculpted in 1957's ''Witness for the Prosecution.''

Both are gripping dramas. Both rely on the element of surprise to make a compelling film. And both are among the best courtroom dramas ever made. Now ''Presumed Innocent'' has joined the ranks.

''Presumed Innocent'' is a Mirage Production, produced by Sydney Pollack and Mark Rosenberg with Susan Solt as executive producer. It is rated R for strong sexual content and unpleasant shots of the murdered victim.

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Motion Picture Association of America rating definitions:

G - General audiences. All ages admitted.

PG - Parental guidance suggested. Some material may not be suitable for children.

PG-13 - Special parental guidance strongly suggested for children under 13. Some material may be inappropriate for young children.

R - Restricted. Under 17 requires accompanying parent or adult guardian.

X - No one under 17 admitted. Some states may have higher age restrictions.