Things are changing in the secret government organization known as the Office of Preternatural Affairs. There are whispers of plans to go public. Special Agent Cèsar Hawke fears a thread of poison in the OPA--a poison seeded by a cult called the Apple. They've already hurt friends, blown cases that should have gone smoothly, and even destroyed cities. If Cèsar can't excise the corruption before the OPA blows itself open, then the poison may spread to all of the government--and maybe the entire world.