When the Goodacre twins show up at Maggie's door with the news that Kai and the youngest Goodacre, Caleb, have fallen in with a mysterious cult, led by a figure out of Navajo legend called the White Locust, she knows what has to be done.

The Goodacres are convinced that Kai's a true believer, but Maggie suspects there's more to Kai's new faith than meets the eye and so she vows to track him down. With the aid of a motley collection of allies, Maggie must battle body harvesters, new-born casino gods and, ultimately, the White Locust himself, and when the full scope of his plans are revealed, Maggie's burgeoning trust in her friends, and herself, will be pushed to the breaking point - and not everyone will survive.