In 1867 Texas, Jett, a girl passing as a boy while seeking her long-lost twin brother, joins forces with Honoraria Gibbons, an inventor, and White Fox, a young Army scout, to investigate a zombie army that is terrorizing the West.

"Nina is a Lipan girl in our world. She's always felt there was something more out there. She still believes in the old stories. Oli is a cottonmouth kid, from the land of spirits and monsters. Like all cottonmouths, he's been cast from home. He's found a new one on the banks of the bottomless lake. Nina and Oli have no idea the other exists. But a catastrophic event on Earth, and a strange sickness that befalls Oli's best friend, will drive their...