Magnus Chase has always been a troubled kid. Since his mother's mysterious death, he's lived alone on the streets of Boston, surviving by his wits, keeping one step ahead of the police and the truant officers. One day, he's tracked down by an uncle he barely knows - a man his mother claimed was dangerous. Uncle Randolph tells him an impossible secret: Magnus is the son of a Norse god. The Viking myths are true. The gods of Asgard are preparing for war. Trolls, giants and worse monsters are stirring for doomsday.

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.

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.

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.

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.