The U.S. Army captured Jace when she was five and locked her away in a secret containment facility specially built for her kind, a prison she's desperate to escape. For Jace, life inside is about staying alive, trusting no one, and finding a way out of the most heavily guarded ten acres on the planet. That's going to be tough since Jace is one of the Army's most valuable assets. Gray, meanwhile, is a "runner." His older sister, Nia, fled with him the night before the Army arrived. Since then, they drift from town to town living off the grid, stealing identities in order to survive.

Although Gray and Nia don't live behind walls, they are trapped in a different kind of prison, one they too are desperate to escape. For them, life is about staying invisible, a tall order since Gray keeps helping people. Now the Army has found out about Gray and Nia, and it can't allow them to roam free. Operating on the theory that it takes one to catch one, the Army has a deal for Jace. Lead a five-man hit squad to hunt them down, and in exchange Jace can leave. Only, someone inside the government doesn't want Jace to succeed. What ensues is a desperate chase through city after city against a backdrop of love and betrayal. During the final showdown, each must confront the question: how far am I willing to go to be free?.