In Baltimore, Maryland, an elite group of plainclothes officers called the Gun Trace Task Force gets hundreds of illegal guns off the streets every year. Secretly, however, these detectives are also robbing people, selling drugs, planting evidence and framing innocent people. When some of the officers go too far, it triggers an FBI investigation that reveals the Gun Trace Task Force as one of the most corrupt police squads in American policing history. Jessica Lussenhop tells the story of the rise and fall of this once-powerful unit of officers, and its leader Sergeant Wayne Jenkins. And she asks: why do good cops go bad?