Continuing directly after Season 5, Mackey and the Strike Team are distraught over Lem's death. Vendrell, overcome by guilt, becomes reckless and suicidal.
Kavanaugh refuses to let the case die and resorts to Mackey's tactics of planting evidence and coercing witnesses to lie about the Strike Team, especially Mackey. Dutch and Wyms begin to suspect Kavanaugh's integrity. Kavanaugh finally confesses to his actions and finds himself under arrest.
Mackey learns from Wyms that the Chief plans to force him into early retirement — and vows to wreak bloody vengeance on Lem's killer before losing his badge.
Wyms learns the Barn could be shut down if no improvements are made by the time quarterly crime statistics are released.
The season concludes with the breakdown of Mackey and Vendrell's friendship, as Vendrell admits having killed Lem. Vendrell threatens Mackey with revealing their illegal exploits should Mackey attempt to arrest him for Lem's killing, while Vendrell gets in over his head with the Armenians.
The Shield was created by Shawn Ryan and is Executive Produced by Ryan, Kurt Sutter, Charles Eglee, Adam Fierro and Kevin Cremin. The series is produced by Fox Television Studios in association with Sony Pictures Television.