In Washington the line between the serious and the ridiculous is very fine," says author Patrick Anderson, who has worked in and around the capital for 15 years. The only time Anderson ever met Lyndon Johnson face to face, for example, was in an airport toilet during the 1960 campaign. Anderson was covering for the Nashville Tennessean. "Johnson said, 'Come on in, boy, and talk to me.' I interviewed him right there in the men's room." After that experience it was only a matter of time before Anderson turned from fact to fiction.

A native of Fort Worth, Anderson, 39, came to Washington in 1961 to join the New Frontier. After four years as a press officer for the Justice Department, he quit to free-lance. His first article was on his former boss, Attorney General Robert Kennedy. "I was not enamored of him when I worked there," says Anderson. "But by the time of his death I think there was a greatness to him."

Anderson continued writing political profiles which ultimately made up his first book, The President's Men, a study of White House advisers, published in 1968. Two political novels followed, disappearing quickly.

His just published third novel, The President's Mistress (Simon and Schuster), seems headed for a much kinder fate. It is an exciting whodunit about the murder of a President's former girlfriend. "I was literally halfway through before I figured out who killed her," Anderson says. "Then it all seemed to fall into place. It was the best experience I ever had." The White House (the President's name is Charles Whitmore) and Justice Department try to cover up details in the young woman's past, but a hidden tape recording finally unravels all. The book is filled with anecdotes about thinly disguised Washington characters who have kept Georgetown dinner parties whispering for years. "We've all heard the stories about the Kennedy, Johnson and Nixon administrations," says Anderson. "But you don't report them. You put them in your novels."

Anderson keeps tuned into Washington by doing magazine articles "as a break from the agonies of book writing and also as research for my novels. The scene with Whitmore and the comedian in The President's Mistress came from a day I followed Vice-President Ford and Bob Hope around the Thunderbird golf club."

In addition to his literary output, Anderson has ghosted books for Turner Catledge of the New York Times, Lawrence O'Brien, the former Kennedy aide who is now commissioner of the National Basketball Association, and convicted Watergate conspirator Jeb Stuart Magruder. "He's a classic example of a man of our time," says Anderson of Magruder. "He did all the things our generation was supposed to do—but he had no values."

In his pre-Washington days, Anderson was a general assignment reporter for the Nashville Tennessean. There he met his wife, Ann, 39, who was the fashion editor. They were married in 1962 and have two children, Laura, 8, and Michael, 7 months.

The Andersons live in an antebellum yellow brick house in Waterford, Va. (pop. 275). The picturesque village in the foothills of the Blue Ridge Mountains is an hour's drive from Washington—just close enough. "In the city you get too involved in the nitty-gritty," says Anderson. "I enjoy sitting here at a safe distance, making my judgments."

Both Andersons became active in local Virginia politics in 1972 and were McGovern delegates to the state Democratic convention. Ann, now a freelance writer on consumer affairs, also presides over a large family garden. ("I just rake the leaves," Pat says.)

If Anderson's latest book (which brought $250,000 in paperback rights) becomes a best-seller as first reviews indicate, he has modest plans. "I would take my wife to Europe and buy my daughter a pony," he says. "The only thing I'm wondering about is whether I have to buy a suit to go on the promotion tour."