Harris finally finds the anonymous eyewitness. Lee decides not to return to New York. Billy is returned to the general prison population to face the consequences of his actions. The D.A. may be forced to drop the case. Season finale.

Fighting crippling pain, Del is determined to continue his investigation and turns to Steve for help. Billy leaves for basic training and finds comfort when he befriends a fellow traveler. The Landwill conflict comes to a head.

Isaac is taken in by a kind stranger. Grace’s union drive is put to the test. Billy fires his public defender. Harris realizes what he has to do.

Cynthia becomes suspicious of everyone as she tries to figure out what happened to Vic. Angela and Del are surprised when they arrive at an urgent police call and things are not as they seem. Lee reconnects with Alejandro when she goes to New York to sign their divorce papers.

Del feels pressure surrounding the Brotherhood as he looks into Vic's disappearance. Lee and Isaac argue about her feelings regarding her job. Isaac’s feelings are hurt when he crosses paths with someone from Russell’s life, while Billy's behavior grows more erratic and causes him to act out.

Billy gets in with a questionable crowd. Isaac travels alone. Harris’ investigation into the anonymous eyewitness continues as a high school football player ODs.

Billy has a new lease on life after finally confronting his past and makes strides to secure his future. Lee is in trouble as Rinna investigates the missing documents. Russell returns to Buell to find Isaac moving on. Angela and Del are wary of mysterious circumstances surrounding a death.

Four months after the shoot-out in West Virginia, Del has returned to the Pittsburgh P.D. while the folks in Buell try to get their lives back on track.

Del invites Vic out to his cabin for a male bonding weekend. Grace goes toe-to-toe with Sue at the District Attorney debate. The town of Buell is rocked by another murder of one of their own, while Steve’s suspicion of Grace grows.

Del and Vic grow closer during their weekend in Buell. Lee grows more suspicious of her law firm as her investigation leads her to surprising evidence. A job prospect presents itself to Grace, and Isaac and Russell bond after a harrowing experience. Steve’s suspicion of Grace and Del grows into an obsession.

Angela is brought into Del's secret plan. Grace receives a promising job offer, but remains worried about Billy’s behavior. Lee and Isaac have a memorial service for their father.

Lee’s involvement in the Landwill case deepens. Isaac receives a surprise visit and Billy’s behavior ruins a dinner party. Del fears for Angela’s safety while Grace misses Del.

A new murder in Buell lights a fire in Steve as he doubles down on his suspicions of Grace and Del. Del continues to investigate the bombing in Pittsburgh while also becoming more enmeshed in the Brotherhood.

Harris races the clock in his search for the anonymous eyewitness. Lee seeks professional advice about whom to protect. Harris’ old Pittsburgh PD partner pays him a visit.

Harris’ investigation continues. Isaac leaves town. Billy and Lee reunite as Buell celebrates a shotgun wedding.

Isaac befriends someone who teaches him the rules of the road. The sheriff searches for evidence in Billy and Grace’s trailer. Billy tells Lee what happened in the steel mill.

In a small rust belt town in southwest Pennsylvania, Chief of Police Del Harris investigates after a dead body turns up in an abandoned steel mill. Series premiere.

Alejandro learns of Lee’s history with Billy. Isaac turns his first trick solo. Harris travels back to Pittsburgh with his old partner to repay a debt.

Grace enlists help in her effort to unionize the dressmakers. The sheriff gets an anonymous tip about the murder in the steel mill.