Twelve-year-old Percy Jackson is about to be kicked out of boarding school...again. No matter how hard he tries, he can't seem to stay out of trouble. But can he really be expected to stand by and watch while a bully picks on his scrawny best friend? Or not defend himself against his pre-algebra teacher when she turns into a monster and tries to kill him? Of course, no one believes Percy about the monster incident; he's not even sure he believes himself.

Jason has a problem. He doesn't remember anything before waking up on a school bus holding hands with a girl. Apparently she's his girlfriend Piper, his best friend is a kid named Leo, and they're all students in the Wilderness School, a boarding school for "bad kids." What he did to end up here, Jason has no idea—except that everything seems very wrong.

After angering his father, Zeus, the god Apollo is cast down from Olympus. Weak and disoriented, he lands in New York City as a regular teenage boy. Now, without his godly powers, the 4,000-year-old deity must learn to survive in the modern world until he can somehow find a way to regain Zeus' favor. But Apollo has many enemies - gods, monsters, and mortals who would love to see the former Olympian permanently destroyed.

As the son of Hades, Nico di Angelo has been through so much, from the premature deaths of his mother and sister, to being outed against his will, to losing his friend Jason during the trials of Apollo. But there is a ray of sunshine in his life—literally: his boyfriend, Will Solace, the son of Apollo. Together the two demigods can overcome any obstacle or foe. At least, that's been the case so far . . . Now Nico is being plagued by a voice calling out to him from Tartarus, the lowest part of the Underworld.

Ana Dakkar is a freshman at Harding-Pencroft Academy, a five-year high school that graduates the best marine scientists, naval warriors, navigators, and underwater explorers in the world. Ana's parents died while on a scientific expedition two years ago, and the only family's she's got left is her older brother, Dev, also a student at HP. Ana's freshman year culminates with the class' weekend trial at sea, the details of which have been kept secret. She only hopes she has what it'll take to succeed.