Vic and Shane's relationship continues to deteriorate as they work against each other to track down the Armenian hit man. The war between the Mexicans and Salvadorans continues, and Vic gets a temporary reprieve from early retirement.
Vic's plan to play the Armenians against the Mexicans could backfire when the wrong man is targeted. Dutch plays hardball to get a witness to a homicide to step forward, and the mayor's new initiative to stop gang violence backfires.
Vic sets up a plan behind Shane's back to get the Armenians on their side. Meanwhile, Gardocki starts getting fed up about Vic continuing to work with Shane, and Dutch tries to get Danni a desk job to protect her.
Vic learns that the federal agent helping them out is in the "blackmail box" and has ties to Cruz Pezuela. Dutch tries to find out if he has a future serial killer on his hands, and Claudette's health is brought into question.
Vic launches his latest plan to get rid of the Armenian threat. However, the main difference in this plan is that, if successful, it will get rid of Shane too. Meanwhile for Shane, a ghost from his past reemerges.
Vic loses his hearing, which is brought up ahead of schedule, and faces early retirement. He also loses favor with Cruz Pezuela and begins playing hardball with Dani, who wants him to give up all rights to their child.
Shane's plan to get rid of Vic and Ronnie falls apart and threatens to be exposed. Cruz Pezuela asks Vic to strong-arm a priest, while David Aceveda joins Vic in working with the feds to bring Pezuela down.
Vic turns in his badge a week early and sets out to find and kill Shane and his wife. However, Ronnie is benched after Claudette shuts down the Strike Team. Meanwhile, Aceveda finds out more disturbing information about Cruz Pezuela.
As everything falls into place for the sting operation to bring Vic down, Shane is desperate for money. Back at the Barn, Ronnie tries to intercept a blackmail package, and Aceveda begins to question Pezuela's "suicide."
Mara breaks her collarbone and accidentally shoots and kills an innocent person when Shane's plan to get more money goes sideways. Meanwhile, Vic contemplates leaving Ronnie out to dry and taking a deal with the Feds without him.
As Vic hopes his immunity deal will help keep his family together, and Shane takes extreme measures to keep his pregnant wife from being charged with murder, Dutch finds he's a suspect in the disappearance of a teenage serial killer's mother.