In 1970s South Boston, FBI Agent John Connolly (Joel Edgerton) persuades Irish mobster James "Whitey" Bulger (Johnny Depp) to collaborate with the FBI and eliminate a common enemy: the Italian mob. The drama tells the true story of this unholy alliance, which spiraled out of control, allowing Whitey to evade law enforcement, consolidate power, and become one of the most ruthless and powerful gangsters in Boston history.

Jesse finds himself struggling to get his job back as the Paradise police chief, and he is forced to rely on his cop intuition to sort through a maze of misleading clues and hidden meaning as he attempts to solve a shocking and horrifying mob related double homicide.