In AD 70 Marcus Didius Falco helps the young Sosia Camillina after she becomes involved in a political conspiracy. Her information leads to stolen silver-bearing ingots and to senators who hope to exploit the unsettled beginning of Vespasian's reign.
Falco travels to Britain, where he works inside a dangerous mine and meets Helena Justina, the senator's daughter assigned to observe him. The investigation connects provincial extraction, imperial finance and a planned challenge to the new Flavian government.