This season explores themes of financial inequality in Boston, specifically juxtaposing the "cloistered existence" of the wealthy Dryden family against the workers of the Big Dig.
Decourcy recruits Caysen to assist with the investigation. However, Caysen finds himself increasingly isolated and alienated from the other officers in his unit.
Sinclair and Letitia Dryden continue to struggle with their "Victoria problem" as they try to manage the fallout of her running away.
Aiming to become Boston's next District Attorney, Decourcy takes on a complicated and murky case involving a murdered police officer.
Jackie and Jenny drop their daughter, Benedetta, off at NYU for her freshman year. While they return home as empty nesters, they find no peace or quiet awaiting them.