Three hundred years ago war scorched the world as we knew it. It was not a bloody war between brothers, but between humans and the earth herself. She fought back against the wicked people bulldozing her jungles, dumping oil into her oceans, and producing gas emissions that tainted her air. The earth had won the war. The ones who survived, The Founders, created a haven inland, free of all flora or fauna, called The Sanctuary. It was split into four Sectors: Alpha, Bravo, Delta, and Echo. The children are taken from their families at a young age and put into training classes, so their earliest memories are driven by being productive members of The Sanctuary. At the age of sixteen, they graduate, going through The Assessment, a simulation to determine which sector they belong in.

Sixteen-year-old Tabitha Nix was assigned to Sector Bravo. During her training to be a soldier in Bravo, the graduates are sent into The Attrition, a final test where she must kill to survive. Tabitha soon finds out the Founders are using The Attrition as a trial run to see of The Wilds, the world beyond The Sanctuary, are inhabitable, even if it means killing off innocent students to do so. The more Tabitha searches for the truth, the more dangerous her existence becomes. She is given a choice: comply or be exiled into the uninhabitable lands of The Wilds?