As Ed McBain talked, the balcony of Mystery Books on Connecticut Avenue suddenly became heavy, oppressive with the humid heat of the Florida peninsula, the damp mold of the subtropics and the decaying flesh of the stinking swamp.

McBain uses atmosphere like a semi-automatic. He is hunting it all the time, to be trapped into his Apple IIe computer.

"Heck, I could charge off all of my life on my income taxes," he said with a wicked look. "It all winds up in the books." In his latest, for instance, the hero "talks about gaining weight in Italy. When we were there I gained eight pounds," McBain said. "I should be allowed to charge it off."

He had come to Washington to autograph "Three Blind Mice," his ninth mystery novel about Florida lawyer Matthew Hope. His wife, author Mary Vann Hunter, had come along. He'd hardly said two sentences about a trip he and Mary Vann, as he calls her, had just finished in Northern Florida before he'd begun to weave the setting into plans for a new novel.

"A couple are on holiday in the lake country. Perhaps the woman disappears. The husband hires Matthew Hope as his lawyer."

Then the editor program clicked in. "It's very risky to take a lead character out of his bailiwick -- all the powers are against him. Back in Calusa, Florida, Matthew -- and his readers -- know the sheriff, the small city, the supporting characters," McBain said. "Readers have a certain expectation level of a series, mystery or mainstream, John le Carre or Jacqueline Susann.

"The hero's history should come out in the course of the series. Someone can ask, 'Where did you go to school.' Or he says, "I was in an automobile accident. That's where I lost the tips of my fingers.' Readers want to come back every time to the familiar setting and characters, learn fresh facts about the character with every book -- of course, nothing very different. They'd hate it if they found out that Matthew was a child-abuser, for instance."

Matthew Hope came along following McBain's own divorce and remarriage in 1973. "I was writing a mainstream novel about divorce, as Evan Hunter," he said. Evan Hunter is McBain's legal name, but not the name he was born with. More on this later. "A lawyer, Matthew Hope, was defending a man who was divorced and remarried. Matthew himself is having an affair -- that didn't go over well, people were more unforgiving back then. The story didn't work as mainstream or mystery. So I gave the advance back and called it quits."

However, it was a story that wouldn't die. A British publisher liked it and suggested a series, all with fairy-tale titles. Hunter then rewrote it in the McBain style. And so the first Matthew Hope novel, "Goldilocks," was published in 1978.

Life Before Hope Evan Hunter was born on Oct. 15, 1926 in New York to Charles and Marie Lombino, first-generation Americans who didn't speak Italian. "Mother would often chastise her father for speaking it," he said.

The young writer, blaming postwar jingoism, in 1953 changed his name legally. "In America, at that time, there weren't any writers with Italian-sounding names ... back then, I perceived -- whether true or not -- a prejudice against people with Italian names. They weren't supposed to be writers or scholars."

Contrary to opinion, he did not name himself for Hunter College, from which he graduated Phi Beta Kappa in 1950. "I thought Hunter was a good name -- aggressive, ambitious, hungry." He knew casually someone called Evan, a writer who looked "mysterious, confident, daring, like a gambler. I liked that."

"And those of your two wives," piped in Mary Vann.

Hunter himself had planned to be an artist. But when he was in the Navy from 1944 to 1946, "we were on a long voyage to the South Pacific. After I had drawn portraits of all the men on the ship and sent them home to their wives and mothers, there was nothing else to draw. There was a radioman's typewriter, all uppercase keys. I began to write short stories on it and send them off to magazines. With the all-capital type they must have looked like an urgent message from the South Pacific."

The other men read his stories and organized ship's pools on which would be published. None was.

To support himself after the Navy and college, Hunter taught in a vocational school in the Bronx, "where the children came after each other with a baseball bat." He based his first bestseller, "The Blackboard Jungle," published in 1954, on this experience.

Hunter also wrote the best-selling novels "Mothers and Daughters" and "Last Summer," several plays for theater, and movie and television scripts, including the adaptation of "The Birds" for Alfred Hitchcock.

His Ed McBain pseudonym is best known for the 40-odd novels in the 87th Precinct series.

Until three years ago, Hunter divided his time between television and novels. "I got tired of hearing 23-year-old television executives talk about motivation. I'm too old for that jazz." He believes that the cinematic style, both in movies and television, is having a strong effect on writing in general.

"A novel can stay in a scene for 30 pages. You have to be out of a scene in a screenplay in three pages. You are always working against the clock," he said.

"I always thought a real writer should be able to write anything. Mozart for instance could write a little piano piece or a score for an opera." As for the difference between Hunter and McBain, "the styles are getting closer."

McBain on the Beat "I've been in police stations everywhere. In Florence, we were walking along the street when we saw one," McBain said. "I went in, and in my halting Italian muttered something about writing the 87th Precinct mysteries. The man at the desk said, 'Hi, McBain,' fingerprinted me to see if I were wanted anywhere and then put us in the back seat of a squad car and took us all over the city."

Sometimes readers suggest ideas. A blind reader wrote McBain that surely Carella, star of the 87th Precinct series, must be making enough money to afford a TDD -- telecommunication device for the deaf -- for his wife. Today, many states require emergency services to have TDD systems, which allow written communication over phone lines. At the time the device was a novelty and McBain had the universal telephone company experience -- he couldn't find out anything about it. But his reader called police departments all over and eventually Florida police called McBain with the information.

Sometimes he hears stories that are transmutable. "Ghosts," an 87th Precinct story, is one of those. A friend told him about a house where his family once lived. "They didn't mind the doors opening and closing by themselves but when they heard the ball bouncing in the attic," he said, "it was time to go."

Editors have ideas for writers too, though McBain doesn't always appreciate them. One editor on "Three Blind Mice" said he caught the key to the solution right away. McBain then went through the book and took out most of the clues. "He said he could still find the references. And I wrote him back saying, 'Cut it out. Sure you know. You're only a virgin once.' "

Whether readers stumble onto the solution sooner rather than later doesn't disturb McBain. "I can't do a lot about it if someone divines or intuits the answer. I don't much care as long as the motive is logical and reasonable. It's the trip along the way."

Scene of the Crime Until a few years ago, McBain's life was divided between the settings of his two principal series, Florida and New York City. (He admits he renamed Sarasota and New York City in his books so "I wouldn't have to check the geography all the time.") He and Mary Vann recently sold their Sarasota house but have kept their New York pied a` terre and a much-photographed Revolutionary War-era sawmill in Connecticut, converted into a house in 1910. "We've worked on it for 15 years and finally it's about finished," Mary Vann said.

Her first book, "Sassafras," set in her North Carolina birthplace, was well reviewed. But though both like her second one better, it hasn't found a publisher yet. "Quiet books are hard to sell, though readers like them," McBain said. They are both working on it and hope it will be published under both their names.

"I word-juggle from 8:30 or 9:30 until I stop for a half-hour to eat my apple with Mary Vann. And then I'm back at work from 4:30 to 6:30. I try to do about 10 pages a day.

"The first burst of writing is the real creation, tapping the unconscious going out," McBain said. "I look up at the end of the day and say, 'I don't know where this comes from.' The rest is donkey work."

Every writer he has talked with "believes in the muse." He grinned and said, "I remember one woman wrote a book of proverbs because she went on a trip and Benjamin Franklin came to her every night and gave them to her."

Oh yes, as one might have suspected, James M. Cain was a strong influence on McBain, as were Raymond Chandler and Dashiell Hammett. When he was growing up, "Ernest Hemingway was the model for all of us: simplicity of sentences, dialogue." Of current writers, he likes Pat Conroy and Ross Thomas, among others.

McBain is no great fan of private eyes.

"I think private eyes, men or women, are mythical figures -- like Rambo or Wonder Woman. They don't exist. Matthew Hope is a lawyer, not a private eye. He hires detectives as fact-gatherers. I don't like amateur detectives either. The only valid crime-solvers are the police" -- as in the 87th Precinct.

In novels as in life, McBain advises: "Call your lawyer if you did it, or the police if you didn't."