The series is an adaptation of Charles Falco's autobiographical book, "Vagos, Mongols, and Outlaws: My Infiltration of America's Deadliest Biker Gangs." In 2003, the protagonist was arrested by US law enforcement for drug trafficking and faced the possibility of a lengthy 20-year prison sentence. Agents from the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) offered him a deal. In exchange for his freedom, Charles had to infiltrate a criminal biker gang. The operation to dismantle the gang lasted three years, but it was only the beginning of Falco's collaboration with the ATF.