Agrippina, the emperor Claudius's niece, reads in the stars that Epaphroditus, a slave, is destined to help raise her son, the future emperor Nero, to the throne of the Caesars. Epaphroditus soon becomes Nero's confidant. Revolutionary unrest strikes Rome, a fiery comet makes a foreboding appearance and the young emperor makes a concert tour of Greece as enemies sprout like hydra's heads. Epaphroditus, fortified by the return of his faith in astrology, discovers that he, Nero's protector, is fated to kill his Caesar.