Vic is no longer the cop he used to be, acting adrift after his past actions have caught up to him. The strike team has been dissolved, leaving Mackey to menial busts that keep him off the streets. When Aceveda moves on to his new City Council position, Captain Monica Rawling takes over the Barn and empowers Vic to implement her controversial anti-gang policies.

Mackey tries to help an old acquaintance find a wayward teenager, but the search quickly turns ugly when the missing teen appears to have been involved in a shoot-out. Meanwhile, Shane heads out into the field with his new partner Army, teaching him shady police tactics and seeing how far he'll go to be partnered up. Plus, Aceveda spends his last day trying to bury Vic for good, which makes things difficult for Rawling trying to take his place.

With Farmington on the brink of a gang war, Monica and Vic race to find the catalyst and stop the bloodshed, enlisting Antwon's help along the way. Still in the doghouse, Dutch decides to take action in thawing the relationship between Claudette and the D.A. Danny and Julien get up close and personal with the Farmington 1-Niners, while Monica looks to Vic for support when the implementation of her property seizure policy challenges her morality.

When Monica puts Vic on the trail of an escaped fugitive in Farmington, he must continue to prove his worth while playing it straight. Claudette gets suspicious of the D.A's motives when she and Dutch are assigned to investigate a major drug dealer who ends up being a minor offender. David seeks an illicit outlet for the troubling feelings caused by his rape. Vic decides to bring Shane closer as his fears about Shane's connection to Antwon Mitchell rise.

A tip from Lemonhead's juvie would leads Vic and Monica to take down a major heroin operation with connections to Antwon Mitchell. Monica continues to battle Aceveda as she tries to sell her new policies to the community, and Julien begins to doubt her methods. Claudette loses trust in Dutch when she suspects he made a backroom deal with the D.A. And Shane and Army find themselves over their heads with Antwon when he blames them for Vic's heroin bust.

Vic challenges Shane and deals with threats to his family; a federal agent arrives in Farmington to investigate a recent wave of violence.

As a local gang war heats up, Vic positions himself as a valuable commodity to the warring parties; Corrine and Cassidy confront Vic.

Claudette encounters a murderous old nemesis; Vic confronts Olivia about her political connections; Dutch's case gets personal.