A mysterious ring holds the key to the greatest treasure of antiquity.

For fifteen-year-old Minerva Brown, it's another miserable, sweltering summer in Rome, the eternal city, a place that in her mind is only eternally boring. Abandoned for a week while her archeologist parents excavate in the Italian countryside, she discovers a peculiar signet ring forgotten among her parents’ artifact crates. When shadowy figures ransack the apartment in search of the ring, she must unravel a maze of baffling clues in a race through Rome to discover an ancient horde of treasure, all before it falls into sinister hands.

A parallel story set two thousand years before follows Gaius Pomponius Strabo, a Roman teen who inherits the signet ring from his dying grandfather during the cataclysmic eruption of Vesuvius. Rescued by a barbarian captain, Gaius becomes an unwitting ally in a journey across the Mediterranean in search of the Isle of Blood, the mythical home of the lost treasure of Pompey the Great. In his adventures to the far reaches of the Roman Empire, Gaius unravels the mysteries of the signet ring and finds himself face-to-face with a family secret hidden for generations, one that could shake the foundations of the empire.