Jackie searches for his absent informant as Jenny searches for purpose, revisiting her passion to become a teacher. Decourcy works up a plan to overcome the town’s infamous “Code of Silence” and get a few suspects to talk. Minogue is assigned a big case, but not the one he actually cares about. Jimmy skips town to visit his kids and finds that, even a thousand miles away, he’s not safe from his problems back home.

Jackie strong-arms Jimmy to get a step closer to finding the presumably dead armored truck guards. Decourcy rattles a suspect called to testify before the Grand Jury. Siobhan learns something unsettling about a leader of the Coalition and worries it could jeopardize the future of the group. Kick’s nightmares continue as she senses her father might be in harm’s way.

As Decourcy increases pressure on the Justice Department, Jackie counters by looking into his adversary’s romantic past. While Jackie’s digging up dirt, Siobhan is planning ahead, focused on starting a family even as Decourcy remains preoccupied by the escalating conflict. Jenny realizes she can’t keep ignoring her mother after an unsettling phone call. With business at the salon all but dead, Cathy Ryan turns to an unlikely income source.

After seeing Holly in the ICU, Jackie reckons with the destructive consequences of his actions, as Rickey Townsend prepares to testify against Decourcy. With violence intensifying between the Copeland Crew and the Braxton Boys, Decourcy, Anton and Siobhan face off in the interrogation room. Grace, left reflecting on her role as a mother and leader in the community, makes an unfortunate miscalculation. And back at the Rohr house, Jenny makes fast friends with the mysterious woman from Belfast.

With Anton on the lam, Kelvin struggles to lead the Braxton Boys and Jackie homes in on Grace. He knows she's hiding something. Sidelined from the investigation, Decourcy finds himself at a disconnect with Siobhan, as he seeks vengeance and she focuses on recovery. When Cathy’s arrangement with Isaac falls through, she pays a reluctant visit to old friends for help. Jenny, meanwhile, finally uncovers the truth about her new friend.

Assuming the involvement of the Campbell brothers at the Copeland territory shootout, Jackie confronts Grace, who can no longer sidestep her sons’ criminal activity. She is forced to make a terrible compromise. Resenting the outcome of a negotiation that he could not take part in, Decourcy finds comfort in the strength of Siobhan, who keeps her head even after tragedy strikes. Jenny insists on helping Maeve, whether or not that means defying Jackie.

As Boston mourns another loss, Decourcy pursues justice in and out of the courtroom. Despite his maneuvering, Jackie discovers that he can’t escape his past, while Jenny decides to finally confront hers. Cathy says goodbye to the root of her struggles. Siobhan sets her sights on a new dream.

Struggling to make ends meet after leaving the FBI, Jackie Rohr gets a job offer from his old mentor. The perks are enticing, but Jackie has no idea what he’s getting himself into. ADA Decourcy Ward eyes a promotion but is diverted by some bad news which lands him back in Brooklyn. Siobhan Quays, having left her prestigious law firm for a position at the ACLU, takes on a case against a construction colossus. Jenny Rohr begins volunteering at a community center where she runs into a familiar face.

When Victoria Dryden runs away from home, Sinclair sends Jackie to find her. Caysen is after justice for BPD Officer Russ Wallace, who he believes may have been intentionally executed by another member of the Strike Force. The incident sparks a dispute at the Ward home in Brooklyn, where Decourcy is looking after his ailing father. While building a case on behalf of her impaled client, Siobhan experiences an intensifying array of symptoms. Diarmuid Doyle tries to help Jenny remedy what has been bothering her, but his plan backfires.