Being Apollo is difficult, especially after being transformed into a human and exiled from Mount Olympus. Apollo (also known as Lester Papadopoulos) has endured both victories and tragedies in his journey to resurrect five antiquated oracles and reclaim his divine abilities. His voyage now brings him to Camp Jupiter in the San Francisco Bay Area, where the wicked Triumvirate of Roman emperors is being prepared for a desperate last stand by the Roman demigods. To survive the assault, Hazel, Reyna, Frank, Tyson, Ella, and numerous other old pals will require Apollo's assistance. Sadly, the solution to their rescue is hidden in the tomb of a long-dead Roman emperor—someone far worse than the emperors Apollo has already encountered.