Assumed Identity

Take a close look at the picture below. That's John Abbott, whose first novel — an assassination thriller called Scimitar — has just been released. His publisher, Crown, is printing 75,000 copies, and they've pumped $100,000 into advertising for the book-big numbers for an unheralded author.

But then John Abbott isn't exactly unknown. In fact, John Abbott is a pseudonym for a very well known writer. How well known? ''I'd say people would recognize my name all over the world,'' the author says through the crackle and hiss of an overseas call. So why is John Abbott, whoever he is, writing under another name? ''I thought it would be fun — and interesting — to see what would happen, review and otherwise,'' he explains. ''Joyce Carol Oates did it (Nemesis). So did Stephen King (The Running Man).''

Abbott submitted Scimitar through his agent, Robert Gottlieb. Richard Merrick, the editor who bought it, says: ''I was Ludlum's editor, as well as the acquiring editor for Silence of the Lambs, so I have some experience with these kinds of thrillers.'' He paid an advance that was ''about a fifth of the size I usually get,'' says Abbott. Although a few people at Crown — including Merrick — know John Abbott's identity, they are sworn to secrecy.

In Scimitar, an undercover Arab assassin devises a plot to poison both President Bush and Margaret Thatcher. Abbott did all the research himself — '' something I always do'' — from scouting out the inner workings of Manhattan's Plaza Hotel to learning how to make nerve gas. ''I called pharmaceutical companies and ordered all the ingredients,'' he says. ''It was that easy. And I had to give the most dangerous element to a Yale friend to dispose of — I couldn't just throw it in the trash.''

The novelist is clearly enjoying his pseudonym and has plans to write more books using it. But what if people guess the correct identity of John Abbott? ''I'll deny it,'' he says swiftly. ''I'll just deny it.''

Our best guess? Could it be Harold Brodkey?