Spenser, a former Boston patrolman who just got out from prison, teams up with Hawk, an aspiring fighter, to unravel the truth behind the death of two police officers.

The true story of Whitey Bulger, the brother of a state senator and the most infamous violent criminal in the history of South Boston, who became an FBI informant to take down a Mafia family invading his turf.

Uptight and straight-laced, FBI Special Agent Sarah Ashburn is a methodical investigator with a reputation for excellence--and hyper-arrogance. Shannon Mullins, one of Boston P.D.'s "finest," is foul-mouthed and has a very short fuse, and uses her gut instinct and street smarts to catch the most elusive criminals. Neither has ever had a partner, or a friend for that matter. When these two wildly incompatible law officers join forces to bring down a ruthless drug lord, they become the last thing anyone expected: buddies.