Two powerful alien forces, the sadistic half-human Brotherhood and the savage Hivers, are determined to destroy all human life on Earth. All that stands between them and the achievement of their goal are the old Earth team and their Raider allies. Enemy actions force the Earth team to deploy on an emergency reconnaissance mission. When all is lost, and only one option remains, they seize it. They launch a desperate near-suicidal assault at the very heart of their vastly superior enemy.