The Reagan family dynamics continue to shift as they deal with everything from gambling and drugs to kidnapping and murder: Jamie (Will Estes) wrestles with his feelings for his new partner; Erin (Bridget Moynahan) and Jack (Peter Hermann) work to figure out their personal relationship; and Danny (Donnie Wahlberg) and Frank (Tom Selleck) clash over an internal investigation of Danny's techniques. As the Reagans faces off against the FBI, the mob, and other officers who don't follow their ethical code, the family bond will both serve and protect them.