A.D. 79 – Rome’s rich and shameless are relaxing in their luxury holiday villas on the coast.  The Imperial Navy is peacefully at anchor at Misenum. Tourists are out and about in the resorts of Baiae, Herculaneum and Pompeii. Only one man is worried. Engineer Marius Attilius Primus has just taken charge of the Aqua Augusta, the enormous aqueduct that brings fresh water to a quarter of a million people in nine towns around the Bay of Naples. Springs are failing for the first time in generations.  His predecessor has disappeared. And now there’s a crisis on the Augusta’s sixty-mile mainline, north of Pompeii on the slopes of Vesuvius. Attilus – decent, practical and incorruptible – assures Pliny, the scholarly naval commander, the he can repair the aqueduct before the reservoir runs dry.  But as he makes his way to Vesuvius he finds there are forces in the world which even the world’s only superpower cannot control.