In first-century-AD Rome, during the reign of Vespasian, Marcus Didius Falco works as a private 'informer,' often for the emperor, ferreting out hidden truths and bringing villains to ground. But even informers take vacations with their wives, so in AD 77, Falco and his wife, Helena Justina, with others in tow, travel to Alexandria, Egypt. But they aren't there long before Falco finds himself in the midst of nefarious doings—when the librarian of the Great Library is found dead, under suspicious circumstances.

Falco quickly finds himself on the trail of dodgy doings, malfeasance, deadly professional rivalry, more bodies, and the lowest of the low—book thieves! As the bodies pile up, it's up to Falco to untangle this horrible mess and restore order to a disordered universe.