Demigod Annabeth Chase has seen some weird things on the New York subway before, but the bizarre two-headed monster—one head wolf, the other lion, both stuffed into a long spiral seashell—beats them all. A dog head wants to join up, but a young blond girl with a white wooden staff blocks its path.

Annabeth, meet Sadie Kane, Egyptian magician and one-time host of the goddess Isis.

The girls follow the strange monster to an abandoned building. Inside, they find Serapis, a once powerful god who drew his might from both Egyptian and Greek magic. To be fully reborn, he needs to get hold of the monster. Annabeth and Sadie fight fire with fire, using a combination of their magical specialties to keep monster and wannabe god apart.

Afterward, Sadie reveals that Setne, an evil magician who’d come back from the dead, awakened Serapis. She warns Annabeth that they have to watch out for him. He’s up to something. . . .