The last of humanity lives within cities surrounded by walls said to reach outer space. The Deep roams the outside, spewing out monsters and raising mountains. The only ones capable of hunting it and freeing humanity are called Rankers, but they refuse to do it, for on top of those mountains are Bosses. Killing them gives power. To kill the Deep is to kill their power. 

But everything changes when a child figures out how to use the Deep to destroy the most powerful city in what is known as the 4th Fall. Terror spreads. A senseless war is brewing.

Nico's parents died in the 4th fall. Faced with the prospects of having what's left of his family evicted out of the city walls for not being able to pay rent anymore, he attempts to become a Ranker, only to fail because he refused to forfeit a match. Now, he must fight with the very person said to cause the 4th Fall for any chance at survival.