The earth sank beneath the waves, and all life was reborn. Humanity was forced to evolve into an aquatic species. They no longer needed air or land, and could live underwater indefinitely. But the ocean was no Garden of Eden: it had long been home to countless billions of creatures. The arrival of aquatic humans upset the balance. They had to fight tiny fish and shrimp for space in shallow waters, battle sharks and tuna in the middle depths, and wage fierce territorial wars against humpback and sperm whales. They would even face the terrifying leviathans of the deep, creatures no human had ever seen before. This is a desperate struggle for humanity's return to the sea, a contest between intelligence and instinct, the weak and the strong, and a deadly battle between a new species and the old rulers of the ocean.
