The novel begins in Hobart, Tasmania, in the 1950's. Richard Miller, a student at the Christian Brothers' school, spends his adolescence recovering from the effects of polio. His one friend is Brian Brady, who is expelled from the school after a tiff with a sadistic Brother. Brian finds work and studies the guitar with Clive Broderick, the "doubleman" of the novel's title, an enigmatic occultist who believes in separate worlds of good (invisible) and evil (visible) reality.

Years later, in the freewheeling '60's, Richard has become a television producer in Sydney. He once again encounters Brian and his friend Darcy Burr, who have been eking out a living as a folk singing duo. Darcy, who has inherited Broderick's Gnosticism, is convinced that his group, the Rymers (which soon grows to include Richard's wife Katrin as lead singer), will achieve fame and fortune.

Richard produces a series of television shows, which, in fact, turn the Rymers into a very hot commodity. They are on the verge of a triumphant tour to England when the threads of their complex story begin to unravel.