For twenty years dictator Eric Sheel rules supreme in the Martian state of Edom while the plague takes his people. Only Harold Sevillus, Earth's premier scientist, knows the secret of how the plague works. Before he dies, Sevillus leaves an encoded message in the brain of his five year-old son, Maric.

Sheel is convinced the message contains the truth about the plague, but he is unable to break the code. As Maric grows older, the message begins to intrude upon his dreams, and then his waking thoughts. At last he is confronted with a choice: Give Sheel what he wants and become part of a horrifying tyranny—or give up everything to save Edom and his soul.