*Read previous Rick Riordan Greek myth books for context
Book 5 in series
Apollo has spent half a year as Lester after his fall from Olympus. After narrowly defeating Caligula and Commodus at Camp Jupiter, he and Meg are returning to New York on an Amtrack. Apollo sees a two-headed snake on the train and is immediately suspicious. When Meg is unconcerned, he tries to figure out if the snake really is evil on the pretense of going to the bathroom. The snake grabs him and utters the next stanza of Apollo's final prophecy, scaring him. Unfortunately, the regular humans can't see any of this because of the Mist and shush Apollo. After the snake delivers its prophecy, it momentarily panics about missing its station before it is killed by an arrow. Apollo turns and sees that some of Nero's henchmen have caught Meg. It turns out Meg knows one of them, a Gaul named Luguselwa. She cryptically tells them to pretend to go to the bathroom near Union Station. She and Meg pretend-fight while Apollo decouples their train car from the rest of the train, completing their escape.
