After billions died in the End War, a small group of survivors found refuge in the Crag cave. Cut off from the outside world, they have no way of knowing if they're the only people left alive. To ensure their survival, they split into four groups: the Hunters, the Harvesters, the Keepers and the Protectors. As generations pass, the population becomes more and more murderous. Killing is so common in the Crag that there are no longer laws against it. Sam, a seventeen-year-old hunter, was left outside the Crag as an infant. Believed to have been a gift from the Sky Gods, there are whispers that Sam is the Sky Child, the one prophesized to bring peace and prosperity to the Crag. Anyone special or different is a target for murder, and Sam is the biggest target of all.