[1] Set in Rome during AD 71, just after the year of the four emperors, the novel stars Marcus Didius Falco, informer and imperial agent.

Falco is in the Latumiae Prison, accused by the spy Anacrites of having stolen lead ingots which were property of the State (as told in the previous novel Shadows in Bronze).

Marcus decides to resume working as an independent, despite the fact that this means he is unlikely to earn enough money to buy himself into a higher rank so that he can marry Helena.

A slave, Hyacinthus arrives at Falco's apartment in Fountain Court to ask him to assist the Hortensii, a trio of nouveau riche freedmen.

During the course of the investigation, Falco is once more arrested and imprisoned in the Latumiae by Anacrites, who brings forth his charges regarding the lead ingots (from the two novels preceding Venus in Copper) to Titus.

Falco persuades Titus to free him, provided he repays whatever is owed for the lead to Emperor Vespasian, and is asked to undertake more work for the Palace.

Continuing to investigate, Falco is beaten up badly by thugs working for Appius Priscillus, a rival of the Hortensii, but is rescued and nursed back to health by Helena.

Falco forces Priscillus to leave Rome, and blackmails the Hortensii into buying his silence by "donating" to a charity set up by Helena.