The murder of an NYPD detective brings Nichols and Stevens to a sleepy seaside town, ruled by one of Nichols' old foes - an Irish mob boss with a reputation for eluding justice.

Welcome to Broad Channel, a sleepy seaside community on the outskirts of New York City. A place where people still believe in hard work, tradition, and loyalty. Here we find JACKIE DOOLEY, an old-school Irish mob boss who runs this town. He's a master at playing to people's weaknesses and pitting them against each other. But above all, he knows how to insulate himself from the law. In fact, he's eluded Detective Nichols on several previous occasions. But the delicate equilibrium he's established is shattered when RYAN FIELDS, a New York detective who's popular with the media, winds up dead on Jackie's turf.

Nichols and Stevens uncover a host of shady characters in Broad Channel, all of whom want something from Jackie, even if though they've already become his pawns. At the center of the case is MOIRA BOYLE, Jackie's former secretary who longs to return to her former boss's good graces and her son EDDIE, a recovering junkie looking for a second chance. Nichols and Stevens also come into conflict with ATWATER, a fellow detective from Fields' precinct who sees their presence as an intrusion on his turf. Atwater warns Nichols and Stevens that Broad Channel is an isolated community where people will do anything to protect their own. As their investigation deepens, Nichols and Stevens come to realize that the bonds of community aren't enough to prevent blackmail, betrayal and murder.