In early 1960s, New York City, officer Terry Muldoon runs the Public Morals Division, a plainclothes unit of the NYPD whose job it is to police vice crimes such as gambling and prostitution. Muldoon juggles various situations, including warning his gangster uncle Mr. O not to challenge the head of the west side Irish Mob and schooling the new recruit Shea how the division actually works. Muldoon also struggles to raise his family in the increasingly violent Hell's Kitchen neighborhood.
Muldoon's aunt asks him to find the person behind his uncle's murder; Sean O'Bannon starts a romance with his best friend's sister; Bullman takes Shea to a private, illegal casino.
Mr. O's wake brings together Muldoon and the west side Irish mob; Muldoon and Patton agree to discuss the case; Muldoon gets a tip about an illegal card game run by the Italian mob.
Muldoon and Latucci take their wives on a double date; O'Bannon has some fun at Shea's expense while arresting a couple of hookers; Kane takes the first step in avenging Mr. O's death.
Rusty takes revenge after making a discovery; Latucci's friendship with an Italian mobster is questioned; Bullman's relationship with a high-end call girl is further complicated; Smitty discovers that being a boss brings unexpected danger.
Muldoon and Bullman find themselves in the line of fire; Sgt. Mike invites Patton to visit him in order to gain some traction with the Mr. O murder investigation; O'Bannon is included in a dangerous pursuit.
Muldoon juggles tensions at home with his family; Lt. King helps out an old flame; Kane and Hopkins plot their revenge; Patton questions his brother's loyalty.
Muldoon must make a final decision about whether Shea should be in Public Morals and puts him to the test; Kane returns to Hell's Kitchen.
Muldoon gets a surprising tip; Patton is officially done with Rusty; Christine plans to leave Hell's Kitchen; Deirdre receives some unexpected news.
The streets of Hell's Kitchen run red with the blood of the Irish mafia; Muldoon treats Christine to a night on the town; Duffy gets surprising news from Deirdre; Bullman's feelings for Fortune intensify.