Peter Maas is knocking back a double Jack Daniel's and talking about what it's like to be a big-time, bestselling investigative reporter and author.

"I get a very cynical view of the world in the work I do," he says. "That's why I get knocked out by a Serpico or a Marie or a Barcella. I really value these people."

They are the heroes of his books: Frank Serpico, the maverick New York cop who exposed massive corruption; Marie Ragghianti, a determined young official who fought government crooks in Tennessee.

And now Maas has a Washington hero, although the guy doesn't think of himself as one -- E. Lawrence Barcella Jr., the federal prosecutor who hunted down rogue ex-CIA agent Edwin P. Wilson, now doing 52 years for smuggling explosives to Muammar Qaddafi's Libya.

In "Manhunt: The Incredible Pursuit of a CIA Agent Turned Terrorist," just published by Random House, Maas tells how Barcella stalked Wilson. The book is written in the spare, taut way of a fictional thriller.

"I have a villain and a hero," says Maas, 56, a stocky man with bushy gray hair and a manner alternately offhand and intense. "I have a writer's dream working here. I have a chase."

The story has appeared in the press; Maas presents it clearly and adds fresh detail unearthed in two years of reporting. To ship 21 tons of C-4 plastique, the most powerful nonnuclear explosive in the world, Wilson had an arms dealer pick it up at depots in New York, Louisiana and Texas. It was packed in five-gallon cans of drilling mud, then trucked to Houston and flown to Tripoli aboard a chartered jet.

Just a matter of the right paperwork, and a little deception.

That was in 1977. Maas says a chunk of C-4 the size of a cigarette pack could kill people and blow a hole in the side of a plane. He thinks some of the plastique Wilson shipped to Libya has been used in terrorist attacks, and that most of it remains in Qaddafi's bunkers. C-4 has a shelf life of 20 years.

"Barcella had stumbled over Wilson by accident," Maas writes. "As other events gradually unfolded, his pursuit became an obsession, personal in every sense of the word. The two men would meet secretly in Italy in a temporary truce. They corresponded and talked over international telephone lines, each trying to outwit the other."

The prosecutor pursued Wilson for four years, often in the face of bureaucratic indifference, finally tricking him into leaving Libya for the Dominican Republic, where he could be taken into custody. The relentlessness of the hunter fascinates Maas.

"This is a terrible town for bureaucracy," he says of Washington. Barcella -- and his other heroes, too -- "are not really an organization person. They don't first think, 'You gotta make a living.' "

Maas traces Barcella's freewheeling intensity to his teen-age years, when he was handed a cancer death sentence and experienced a miraculous remission that left him feeling liberated, unfettered by conventional worries about success. Now, Maas says, Barcella is a maverick who "doesn't realize it himself. He thinks he's true-blue."

Barcella said by phone that he's read the book and "it is certainly very flattering. I don't agree with everything in it . . . I certainly was not alone in either doing the work or putting the case together."

Maas is a little bit of a maverick himself. He had always wanted to be a fact-digging reporter, and when he got out of the Navy in 1955 he went to work for Collier's magazine. He gravitated toward the "investigative" side partly because he liked exposing crooks, partly because it meant he didn't have to work in the office.

"I can't work for anybody," he says now.

On Tuesday Maas spoke, along with David Stockman, at The Washington Post's Book & Author Luncheon. Afterward, he claims, his autograph seekers outnumbered those of Stockman, who was peddling "The Triumph of Politics: Why the Reagan Revolution Failed."

Maas received a "hefty six-figure" advance for "Manhunt."

"I didn't get $2.2 million for it," he says, referring to Stockman's advance. ". . . I'm not really in the big leagues." Reflecting for a moment on this modest statement, he amends it: "Well, I'm in the big leagues, but I'm not Reggie Jackson."

"Serpico" sold 2.7 million copies and brought $350,000 for the movie rights. "Marie" went to the movies for $650,000. "The Valachi Papers," which is out of print, will be reissued by Pocket Books in September.

"I never submit a written outline," Maas says. "I say, 'I've got this idea . . .' "

And the money flows.

But 22 publishers turned down the idea for "The Valachi Papers," which finally came out in 1966. "They said, 'The Mafia doesn't sell.' What I was really doing was starting a new industry. This was before 'The Godfather.' "

Maas has always been a New York guy. He grew up in Manhattan and says he likes the rumble of the city outside as he writes in the apartment he shares with his wife of three months, Suzanne Jones, a caterer.

He attended Duke University, where Clay Felker hired him for the student newspaper. At Collier's he found himself in the company of Pierre Salinger, Raymond Price (later a Nixon speechwriter) and George J.fs,1 W. Goodman (now writing under the pen name Adam Smith).

In those early years Maas also worked for The Saturday Evening Post, Look magazine and The New York Herald-Tribune. When Felker started New York magazine in 1969, Maas joined the staff with Jimmy Breslin, Tom Wolfe, Gloria Steinem and others. His friend Steinem calls him a "liberated male," he says, because he "treats both sexes with equal contempt."

Over the years Maas has developed an approach to investigation that emphasizes not so much the revelation of shocking facts as the explication of events. He has a certain humility now, is content simply to spin an interesting yarn.

"When you're an investigative reporter, there's a certain ego in that. You think you're gonna change the world, and at some point in your life you discover you're not changing the world. You're changing faces."

"Manhunt" is fact-packed, and far from preachy. Wilson was able to make millions on the side and hoodwink the Washington power elite both during and after his career in the government, but the book doesn't offer any analysis.

"I'm not sure books should draw conclusions," Maas says. "I think they should make people think . . . I could have gone much more into the agency, but I really wasn't writing about that."

What he was writing about, he says, was "character" -- people and their motivations. He didn't break the Serpico story; he became fascinated with the man.

"I realized that character was all-important. If you have good characters, the story follows . . . I never make an outline. I write nonfiction as if I'm writing a novel."

The idea for "Manhunt" came to Maas one morning while he was reading the paper. An item about Wilson mentioned his fabulous estate, Mount Airy Farms, in the Virginia hunt country. "And I'm thinking to myself, 'How can a guy be living next to the Mellons and Sen. John Warner and Elizabeth Taylor and Jack Kent Cooke' " on less than $30,000 a year from the government?

"I thought, 'This is the Great Gatsby of the spook world!' "

Maas talked to Washington Post reporter Bob Woodward, who had written an early story about Wilson. Woodward and others told Maas that Barcella was the "unsung hero" of the saga.

After five months of hectoring, Barcella finally agreed to talk -- not about legal details of the case, Maas says, only about his feelings at various stages of the drama.

The author had his story, and he fell into his workaholic mode. After two years of reporting -- interviewing scores of people and talking some into giving him copies of classified documents -- he spent a year writing.

"We live in a very institutionalized world," Maas says. "It's wonderful to get it down to individuals."