To read "The Professional," the fabulous first novel of writer W. C. Heinz, is to visit a world that no longer exists, even to wonder whether it ever did.

Heinz, a deeply, broadly respected sportswriter in the middle of the last century, wrote "The Professional" in 1958, but it has just been released again by Da Capo Press. It is the story of middleweight Eddie Brown, who's 87-3 and preparing, finally, for his shot at the crown. It's also the story of Doc Carroll, his curmudgeonly manager-trainer, and of Frank Hughes, the magazine writer shadowing Brown as he trains, and of the pugs, both unsavory and unsung, who gave their life to the game.

As plot, it is compelling, with doubt of the outcome surviving until the last. As prose, it is spare and sinewy. And as a period piece, it is instructive: Heinz sets his story against a real New York that no longer exists: the Garden is still on Eighth Avenue between 49th and 50th, the Thruway is still a novelty, and automats are still open.

He describes a world that no longer exists either: "Every man's in a fight, Eddie, no matter what business he's in," Hughes says to him, trying to explain why the fighter's wife isn't always in his corner. "The woman can try to understand, but she's really just a spectator." And there is a certain quaintness of expression, such as when Hughes begins a thought, "If I am permitted the pun . . ."

Other scenes straddle the bygone and present, such as when a TV show's advance woman comes to training camp to arrange an interview. Carroll is against it, but ultimately allows Brown to appear out of chivalry toward the woman. His first impulse is borne out when the interviewer attacks, first by pushing around Brown's bewildered mother on air, then by making Brown out to be a savage.

He's not, of course. Heinz's Eddie is a decent man, respectful and true to old friends, even when he's fighting for the world championship. And he's not just some mug; he's intelligent, and it's going to be on that basis, not brutishness, that he wins the title, if he does.

Carroll, meanwhile, is smart too. He's been working fighters for 40 years, and everything he's learned has gone into getting Brown to this brink. He's also a control freak, feeling free to instruct Brown on when to go to the bathroom, and to answer for him when the questioner wants to know how he feels. It's quirky to see an intelligent adult like Brown submit like that, but it's part of their deal.

Hughes is the narrator, his constant presence justified by his magazine assignment to chronicle a challenger's rise to champion. It's fair at least to wonder if Hughes isn't Heinz's stand-in; Heinz made his name writing for Life, Collier's, and the Saturday Evening Post.

Regardless, both men clearly love the fight game, as evidenced by this exchange between Brown and Hughes. It also exemplifies Heinz's dialogue:

"How come you like boxing so much?" Brown asks.

"Because I find so much in it."

"How do you mean?"

"The basic law of man. The truth of life. It's a fight, man against man, and if you're going to defeat another man, defeat him completely. Don't starve him to death, like they try to do in the fine, clean competitive world of commerce. Leave him lying there, senseless, on the floor."

"I guess that's it. I don't know."

"Look, I'm not supporting this. I'm not saying it's good. I'm just saying it's there. It's in man, all men."

As a style, it carries the story well and rapidly, sometimes almost too rapidly; the writer's disdain for attribution sometimes required backtracking to find out who said what, when. As a defense of boxing, it helps to explain its popularity then and its existence now, even in the age of rampant fraud, egotism, and biting Tysons.

Heinz finds truth not only in the ring, but within himself as a journalist, when Hughes admits to himself "the growing weight of my own involvement." The rule book says, journalists don't become a part of; just record and report. But as this book says, that's not how it works: People take sides, and journalists are people.

Heinz, who today is 85 and living in Dorset, Vt., went on to co- write the Vince Lombardi autobiography "Run to Daylight!" and the novel "MASH," which are some pretty decent credits. But on publication of "The Professional," there was no widespread acclaim; there was just one plaudit, and a good one: a cable from Ernest Hemingway six days later that said: " `The Professional' is the only good novel about a fighter I've ever read and an excellent first novel in its own right.' "

Naturally, the comment graces the cover of "The Professional," and a second great writer is invoked as well: Elmore Leonard, who wrote the foreword. In it, he declares that the novel was the only time he felt moved to write to a fellow author in admiration. It was the duo of Papa and Dutch that led me to pick up "The Professional." Now, having read it, I know that there were not two great writers' names on that cover, but three.