Two hundred years ago, the great Ark Horizon Alpha escaped a doomed Earth and went searching for a new home. The passengers landed on Teu Ceti expecting paradise, but instead they discovered a planet stuck in its own version of the cretaceous period. The humans' one defense against the dinosaurs is an electric fence, built from the remains of their space shuttles. Now Eden base has only days of power left. With most of the adult men dead, rookie soldier Caleb Wilde and his unit of teenage boys leave the electric fences of Eden in search of a reactor core lost deep in the jungle.