Where better to enjoy the last days of summer than on the beautiful Bay of Naples? All along the coast, the Roman Empire’s richest citizens are relaxing in their luxurious villas. The world’s largest navy lies peacefully at anchor. Only one man is worried. The engineer Marcus Attilius has just taken charge of the Aqua Augusta, the enormous aqueduct which brings fresh water to a quarter of a million people. Springs are failing. And now there’s a crisis on the Augusta’s sixty-mile main line – somewhere north of Pompeii, on the slopes of Mount Vesuvius.