The year is 37 A.D., and Rome faces a dangerous threat in the form of a new religion whose doctrines could undermine the entire foundation of the Empire. Sextus Marcellus Ennius, one of Rome's top spies, is dispatched to Jerusalem to investigate this cult and discredit its founder, a criminal named Jesus-bar-Joseph, who was rumoured to possess supernatural powers and reputedly rose from the dead after his execution. But as Sextus searches for the truth, he will be faced with dangers on all sides: the intrigues of the mad Emperor Caligula, traitors among his fellow Romans, and murderous religious zealots. And when he finally unravels the mystery, the truth is more terrible than he could have ever imagined ...