In early ‘90s Boston, racism is endemic and crime is widespread. Jackie Rohr, a renowned FBI agent whose methods are not exactly by the book, does not mind the status quo. But Decourcy Ward, the new Assistant District Attorney in town, wants to uproot the corrupt system. The two form an unlikely, and obligatory, alliance to take down a gang of armored truck robbers from Charlestown.

After an eventful Sunday at church, Decourcy finds out he has a new powerful enemy in town — one that puts his wife Siobhan in an awkward position. Jackie is stirring up trouble in his own home, and his distrustful mother-in-law Rosa is onto him. Investigators Hank Signa and Rachel Behnam look into an unsolved missing persons case connected to the robbery in Revere. That could mean trouble for Frankie Ryan, who's busy laundering his most recent loot and, with the help of his brother Jimmy, getting carried away in the process.

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.