Rome, AD 70. August, and it's sweltering. For Marcus Didius Falco, tough private investigator, the summer holds few prospects other than spying on the senators' faithless wives. Then Falco meets the young, beautiful Sosia Camillina when he saves her from the attention of two idiot thugs, an encounter which seems to open new horizons. Then the appearance of a stolen silver pig - a silver-bearing ingot of lead - leads Falco to a plot to overthrown Emperor Vespasian. A murder swiftly follows and Falco finds himself in Britain, disguised as a slave in order to find out how, and by whom, the ingots are smuggled.