Agent Seventeen has quit. But whoever wants to become Assassin Eighteen must track him down and kill him first. So when a bullet hits the glass inches from his face, he knows who fired it—doesn't he?

It turns out that the sniper isn't the hardened killer he was expecting. It's Mireille—a mysterious silent child abandoned in the woods with instructions to pull the trigger. Reuniting with his spiky lover, Kat, Seventeen has to protect Mireille and discover who sent her to kill him and why. But the road he must travel is littered with bodies. And the answer will blow apart everything Seventeen thought he knew.