"I knew I was not alone. They would never leave until every last one of us was gone." Sawyer Russo has sworn to protect humanity, and as a Watcher she’s done just that. But the Bots and Carbons that took her city are evolving, and they start picking the Watchers off one by one. One last rescue mission will change everything. When someone betrays them, the line between friend and foe is no longer easily drawn. Sawyer made a vow, and she will fulfill it, even if it means ending the person who deceived them, no matter who it might be. It all comes down to one choice... Who can she save? And who does she have to let go?