Imagine a whole series of separate universes, made to suit the whims of a race of super-beings. Imagine these universes with their own laws, cultures, creatures, and ecologies -- all existing solely to please the fancies of their individual master.
Then imagine one such universe constructed as a diabolical trap to destroy a single person -- the man called Robert Wolff, one of the race of universe-makers, and once of Earth. When the satanic Master-Lord, Urizen, kidnap's Wolff's wife, he forces Wolff to enter the deadly universe of ambushes, filled with every kind of tortuous snare that the evil mind of the Master-Lord can advise.
Wolff has only his courage and his wits with which to combat this cosmic maze -- unless he can perform a miracle, he and Chryseis are doomed.