Sharing a ewer of Spanish red with his old friend and new partner Petronius Longus, Marcus Didius Falco is on the spot when a man cleaning the local fountain makes a gruesome discovery: a human hand that suggests its owner met a terrifying fate. Naturally, Falco and Petro, formerly of the Vigiles, want to seize on it as their first big case. The officials of Rome, however, prefer to hush up the incident, since a population that riots at the drop of a toga might run wild if body parts are polluting their drinking water.

Soon other delicate, dismembered hands are being found in Rome's two hundred miles of aqueduct. Falco and his partner suspect a serial killer is at large, linked to public festivals, and likely to strike again at the upcoming Roman Games. Even a detective as astute as Falco may not spot a twisted mind in a crowd of 250,000. And if Falco loses this race with time, another pretty victim will make a deadly splash.