Santrauka: Marcus Attilius Primus arrives in the Bay of Naples from Rome to take charge as aquarius (hydraulic engineer) of the Aqua Augusta, the aqueduct that supplies water to Pompeii and eight other towns along the Bay of Neapolis, the ancient term for the modern day Bay of Naples. Attilius' predecessor as aquarius, Exomnius, has mysteriously disappeared as the springs that flow through the aqueduct begin to fail, lowering the supply of water available to the region's reservoir, the Piscina Mirabilis in Misenum. Then, dramatically, the flow of water stops entirely. Attilius concludes that the aqueduct must be blocked somewhere close to Mount Vesuvius, since reports claim that the Augusta has failed somewhere before the town of Nola, meaning that towns from there through Naples and Misenum are without any water supply. With aid from Pliny the Elder, whose fleet is docked at Misenum, Attilius assembles an expedition to travel to Pompeii and then on to the blocked section of the Aqua Augusta. While Attilius' expedition is there, the aquarius himself becomes embroiled in a plot of former slave and land speculator Numerius Popidius Ampliatus to become the provider of low-cost water to Pompeii, which Exomnius, the previous aquarius, helped him do while stealing from the imperial treasury. Attilius' questions and studies make Ampliatus suspicious of what Pliny the Elder later discovers – thousands of Roman sesterces at the bottom of the reservoir that should have gone to Rome and which Attilius' predecessor had intended to retrieve once he'd emptied the reservoir. Ampliatus' daughter Corelia gets Attilius the proof he needs from her father's written records when he's working on the Augusta near the foot of Mount Vesuvius. The eruption of Mount Vesuvius on August 24 overwhelms Pompeii, Oplontis, and Herculaneum, Attilius risks his life and comes back to Pompeii to find Corelia. Attilius and Corelia dig their way through the aqueduct tunnel which the springs are beginning to fill--which carries a high risk of drowning. Ampliatus is killed when he refuses to evacuate the city, and Pliny dies when the sailing ships he tries to evacuate the citizens in are overwhelmed by the volcano. At the end of the book Attilius and Corelia enter the aqueduct just as the waters are coming back to full flow. The last sentence of the novel reports a local legend that a man and woman emerged from the aqueduct after the eruption - implying that Attilius and Corelia likely survived the trip up the aqueduct.