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.

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.

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.

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.

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.

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.

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.