"The Shield" enters its fourth season with Vic Mackey adrift after his past actions have caught up with him. He's no longer the cop he used to be - the Strike Team has dissolved and he's stuck babysitting a menial surveillance sting that keeps him off the street. With Captain Aceveda moving on to his new City Council position, Captain Monica Rawling prepares to take over the Barn and implement her controversial anti-gang policies.
As Monica is forced to defend her crime-fighting tactics, Vic's pursuit of a killer creates problems for Antwon, while Dutch's secret deal with the D.A.'s office gets him and Claudette assigned to a murder investigation.