Set in Rome, southern Italy, and the Bay of Neapolis during AD 71, just after the year of the four emperors, the novel stars Marcus Didius Falco, informer and imperial agent.

Marcus Didius Falco and a group of the Praetorian Guard under the captaincy of Julius Frontinus are disposing of a decomposing corpse.

In his position as imperial agent, Falco is involved with the tidying of the conspiracy (as related in the previous novel The Silver Pigs) and the emptying of the traitor's house.

He returns to the palace to be informed that Anacrites had been unable to locate Barnabas; the freedman immediately becoming suspect in the arson and death.

Barnabas is once more implicated in an attack on the Deputy Priest, apparently mistaking him for Gordianus who would normally have been conducting the ceremony, but Falco is forced to return to Rome without tracking him down.

Falco manages to track down Aufidius Crispus at the Villa Poppaea, where the senator is hosting a sumptuous banquet in order to gain support for his future political moves.

After several days, Falco catches up with him, only to discover that "Barnabas" is in fact Atius Pertinax, the ex-husband of Helena Justina, believed dead.