Layla has spent her entire life in the Redoubt, one of the last bastions of humanity in a ravaged world. She's never been beyond the Redoubt's walls; only Crossers, with their special training and survival skills, are permitted to venture into the shadow-haunted wastelands. When Layla's father falls ill, she knows she needs to find a cure. But no such medicine can be found within the Redoubt. Instead, her only chance is to pass a series of gruelling trials to become a Crosser, and then to strike out into the wilderness - where the feeders are.