COME MORNING. By Joe Gores. The Mysterious Press. 218 pp. $15.95.

RUNYAN is a thief by trade, a mountain climber by avocation. He enlists in the service as an alternative to a jail sentence. In Vietnam he saves a gut-shot buddy's life. After his discharge he steals for six years, pulling burglaries, working alone, never getting caught.

Then Jamie Cardwell, whose life Runyan saved once already, asks another favor. Cardwell's on the hook with a loan shark; to get out from under, he brings in Runyan to burglarize the wholesale diamond merchant's where Cardwell is employed as a guard. Runyan is furnished with a key, but on the way out Cardwell shoots him. The damned ingrate wants it all.

Runyan, wounded, manages to get away and hide the diamonds before he's captured. And now it's eight years later, and Runyan is paroled after serving seven years of a 15-to-life bit at San Quentin. As the book opens, author Joe Gores walks us through the release process:

"Getting closer to the outside skin of the prison was like coming up from a deep dive, the gloom around you turning progressively lighter, more delicate shades, as more and more sun filtered through, until you burst out with a huge WHOOSH of spent air."

Dave Moyers, an insurance investigator, has arranged Runyan's parole; if Runyan will turn in the $2 million dollars worth of uncut stones, Moyers will pay him a finder's fee and let him keep his freedom. But Moyers is not the only person interested in Runyan and his diamonds. He's barely through the black iron gate when Louise shows up to offer him a ride. Would you believe that she's a writer, eager to interview Runyan in connection with a book she's planning?

You wouldn't? Neither would Runyan. He can't trust anyone, and neither should you, because nobody is on the up-and-up in this taut, perfectly-plotted novel, and it won't do you a whole lot of good to know this in advance. Joe Gores has an endless supply of surprises and crisscrosses, of thrusts and counterthrusts, and they're all fair, and they all work.

Joe Gores is one of the better-kept secrets in crime fiction. His first novel, A Time of Predators, was a powerful story of an ordinary man's extraordinary vengeance. Three novels followed, chronicling the affairs of a San Francisco detective agency and creating a new form, the private eye procedural. Gores' Interface is a brilliant suspense novel with what I recall as the most stunning surprise in contemporary mystery fiction. Hammett is a tour-de- force of another color, a period piece in which the classic hard-boiled writer is himself cast as a detective.

Come Morning is Gores' first novel in eight years. How come? Did he pass the time in Q, sharing a cell with Runyan? Metaphorically, perhaps; over the past decade he has written a whole slew of screenplays and teleplays. While I'm sure his efforts have brought satisfaction to many, not least of them the author's accountant, I'm happy to see him back in book form again.

Come Morning is a pure pleasure to read. Please understand that the basic ingredients are nothing new. One man has something -- spy secrets, a black bird, a fortune in diamonds. Others want to take it from him, by force or stealth or subterfuge.

Runyan is a big reason why this book works so much better than others of its ilk. He is at once wholly credible as a thief and yet likable and sympathetic. He is sharp enough to be suspicious of Louise, human enough to fall in love with her anyway. We know him (even if we can't tell if Runyan is his first or last name) and we care what happens to him.

The supporting cast is every bit as compelling. Louise is convincing in her ambivalence, whorish one moment and love-stuck the next, finding elements of her real self as a mob moll and as a would-be writer. Taps Turner, a friend of Runyan's from prison, runs a funeral parlor as a front for a gambling den. Taps' girl Grave is an expert pilot, a math wizard, and a good enough actress to dazzle a security guard with her performance as a hooker. Runyan's teamster brother Big Art Elliott, diamond dealer Gatian Sheridan, a loan shark, a stamp- collecting parole officer, the treacherous Cardwell, the relentless Moyers -- every character rings true and remains clearly etched in the mind.

The plot is a honey, intricate, logical, fair, and constantly surprising. Gores, himself a licensed private investigator before he turned writer, has a P.I.'s resourcefulness in devising ways for the characters to trace and check on one another. Like Ross Thomas, he is very good at the sudden shift of allegiance, the abrupt, unanticipated burst of violence. Kicked in the groin, the loan shark Tenconi claps his knees together and sinks slowly to the floor, "making the sound bath water makes leaving the tub."

Within the mystery field, Gores has won awards and fans. He deserves a wider audience, and this book should get it for him.