William Martin became novelist via Hollywood

A delayed commuter train held up my interview with author William Martin. I had managed to telephone ahead, and Mr. Martin agreed to wait for me at his publisher's office. When I arrived 45 minutes late, Martin was unperturbed. He had the manuscript of his next novel with him, and he had used the time to work out a troublesome plot point.

This incident seems typical of Martin's approach to his writing career: Make the most of the opportunities presented. Combined with his writing talent, this attitude has resulted in two best-selling novels, ''Back Bay'' (Crown, 1980) and ''Nerve Endings'' (Crown, published earlier this year). His third novel, ''The Rising of the Moon,'' will be published in 1986.

Although he is making a name as an author, Martin says he originally wanted to be a movie director. Shortly after graduating from Harvard in 1972 with a BA in English literature, the native Bostonian and his wife, Christine, headed for Los Angeles. Martin earned a master's degree from the University of Southern California film school and won the Hal Wallis Screen Writing Fellowship for his first screenplay, an adventure set during the California gold rush. Firmly convinced that writing screenplays would be the best way to break into the movie business, Martin wrote a second one, an adventure set during California's water-rights war of the 1920s.

Martin had fallen in love with movies as a child in the '50s and '60s, especially with such larger-than-life adventures as ''Mutiny on the Bounty'' and ''Bridge on the River Kwai.'' By the time he earned his MA, however, Hollywood wasn't making that kind of movie anymore. After reading his screenplays, one producer said to Martin, ''The way you write you ought to write a novel.'' He and Christine returned to Boston, and that's exactly what he did.

His first book, ''Back Bay,'' is an eight-generation family saga that weaves together the past and present in a story that traces the journey of a Paul Revere silver tea service, which mysteriously disappeared from the White House in 1814, when the British marched on Washington, and ended up buried in Boston's Back Bay.

Martin says, ''I had the idea for 'Back Bay' kicking around . . . since about the fourth grade, when I had studied the geography of Boston and had speculated whether there might be buried treasure sunk down there beneath the landfill.''

The idea for ''Nerve Endings'' came from a bumper sticker that read, ''Bequeath thy kidneys.'' Martin says he wondered ''what would happen if the recipient of a kidney suddenly became interested in the person who had been the donor . . . and eventually tried to repay the donor by . . . taking up causes that motivated him in his life.'' After extensive research on organ transplantation, Martin discovered that, although the anonymity of the donor and the recipient is preserved whenever possible, his premise could be valid.

James Whiting, the main character of ''Nerve Endings,'' is a young Boston advertising copywriter who has a kidney transplant in the opening chapters. He accidentally discovers the identity of the donor, Roger Darrow, a television producer killed while filming a documentary about the cable television industry, focusing on the powerful MacGregor Communications empire. Whiting travels to California, where he meets and falls in love with Darrow's widow, Jeanne. After viewing Darrow's videotapes, Whiting and Jeanne trace Darrow's route across the country to find what he was looking for, followed closely by MacGregor henchmen. They uncover a political plot involving MacGregor Communications and learn some surprising things about themselves and about Roger Darrow.

''Nerve Endings'' is a fast-paced, action-packed, highly entertaining novel. The film rights have been sold to MGM, and a screenplay is being written, though not by Martin himself.

Is he still interested in working in the movies?

He replies: ''Sometime in the future, especially if the book I'm working on now attracts attention as a movie, I would be interested in writing the screeplay. But as I get older, and the more I understand about the craft of writing novels, the more I want to learn about it and the more I want to practice this craft rather than the craft of screenwriting, because the difference between a screenwriter and a novelist is that the screenwriter . . . is considered the first of many hired hands, whereas the novelist is the producer, director, writer, and actor all rolled into one.''

If the opportunity arises, he'll take it. In the meantime, there's that third novel he's writing, ''The Rising of the Moon,'' set in Boston and Ireland in the six weeks before Ireland's Easter uprising of 1916. And, knowing William Martin, I'm sure he already ha sthe idea for the fourth.