Stoney Winston ( Double Exposure , Scribner, 1985; Truck Shot , Macmillan, 1989) currently works as a gag-writer for a wildly popular television quiz show. When the show s producer suspects a beautiful contestant of cheating, she sends Stoney to find out how. Soon two murders, some missing pornographic pictures, and a series of graphic letters threatening the nubile-but-dumb game-show hostess give Stoney cause for alarm. The author maintains a light touch, however, so the Hollywood settings, diversionary plot, and stock characters breeze right along.