Two months have passed since the events of Burning Sky, and things have changed for Nathan Richards. Incensed by Kukulkan's victory and the unexpected loss of his mother, he refuses to play The Game until he knows what the stakes are-- until he meets a girl named Mavis in the field museum who died mysteriously at the Chicago Columbian Exposition, more than 100 years ago.

With the help of Alyssa and his friends, he will have to immerse himself in the Chicago Expo and the deep rivalry between Thomas Edison and Nikola Tesla to learn Mavis's forgotten secret. This time, though, Nathan might have an advantage. Ah Puch, the Mayan god of the underworld, has offered Nathan his assistance against Kukulkan . . . no strings attached.