Poseidon's Gold is a 1993 historical mystery crime novel by Lindsey Davis and the fifth installment of the Marcus Didius Falco Mysteries series. Set in Rome during AD 72, the novel stars Marcus Didius Falco, informer and imperial agent. The gold in the title refers to the treasure, taken by Falco's brother Festus for one of Festus' wild schemes and which now appears to have gone down with the ship, returning to Poseidon.