Straightlaced and uptight, FBI Special Agent Sarah Ashburn can be actually a detective having a reputation for excellence--and hyper-arrogance. Shannon Mullins, certainly one of Boston P.D.'s"finest," is both foulmouthed plus has a very short fuse, also uses her gut instinct and streetsmarts to capture the most elusive criminals. Nobody has had someone, or a friend for that matter. They turned into the last thing anybody Buddies when these two law enforcement combine forces to bring down a ruthless drug lord.