They're upstairs. They're downstairs. They are everywhere and nowhere. They want to conquer the Earth. They want the Earth to remain with us. Others have come to destroy humanity. Others have come to save him. But beneath these mysteries lies a simple truth: Cassie is a victim of betrayal. Like her comrades: Ringer, Zombie, Nuggets. Like the seven and a half billion inhabitants of the planet. First, people were betrayed by others. Then people betrayed themselves. The last battle for life will take place neither on land nor on the sea, not in the mountains and not on the plain, not in the jungle and not in the desert. It will end where it began - at the starting point. And the leading edge of this battle is the human heart.