Jan, a mild mannered millionaire, is present when a copper urn is opened. The urn contains a genie. The genie kills the person who opened the urn and then puts a curse on Jan with Eternal Wakefulness. The curse makes it so that when Jan goes to sleep his consciousness is transferred to another world where humans are slaves to the genie and he is a swashbuckling rogue named Tiger. In the Slaves of Sleep, Jan must come to terms with his other self and use his wits and Tiger's brawn to save both of their lives in both worlds. He finds out that the other world, where he is Tiger, is a sleep world where human souls go when they snooze. Every person on one world has a doppelganger on the other. Jan is greatly influenced by Tiger and vice versa. Eventually, the two diametrically opposed personalities combine and Jan becomes a scholar and a hero. Unfortunately, he is facing murder charges in the real world and is being hunted by the genie in the sleep world. In the Masters of Sleep Jan is accused of insanity and faces brain alteration while Tiger is again a lowly sailor with a fleet of genie after him.