Caged in frustration by having to work alongside the reptilian Chief Spy Anacrites, Marcus Didius Falco devises the perfect escape; become a tax collector in the "Great Census of A.D. 73".

If his services are accepted by Vespasian and Titus, he may even rise high enough in the middle ranks to marry his long-suffering companion, Helena Justina.

But a toothier job roars his way when the Empire's prized lion is mysteriously stabbed to death and Rome's star gladiator is found murdered.

Now, Falco must enter the dark and desperate world of the Coliseum to hunt for a madman who must kill - or be killed.