A perfect citizen. A captured rebel. One decision could destroy them both... As a Regulator, seventeen-year-old Katherine Holliday’s duty is to protect the people of the Federation from a group of violent rebels who have exiled themselves to the mysterious wilderness. When one of these rebels is captured within the Federation, the government leaders propose an alternative to execution, a procedure they call Reintegration. The procedure involves erasing the rebel’s memory and attempting to make him a member of society. The rebel, a young man named Matthew, is not the violent criminal Katherine expects, and she can’t help but befriend him. A few weeks after Matthew’s Reintegration, Katherine realizes the procedure failed and she is now presented with a choice no one else can help her make. Can she warn her superiors that Reintegration failed, which could mean death for Matthew? Or will she defy everything she knows to help him escape—and risk her own execution?

Katherine Holliday has left behind her life in the Federation. She is ready to start a new one with Matthew and the Intolerants. But it isn’t long before the Underground leaders send her on a mission that takes her back to the Federation. Katherine finds herself in City 1, with the help of new and unexpected allies, in an attempt to locate information that could help the Underground escape the Council’s battle plan called Project Endgame. But the Federation has changed and the Council is more desperate than ever. While back in the Federation, Katherine uncovers a tangled web of deception and manipulation. Haynes isn’t the only one with secrets, and the question of who to trust becomes harder to answer.