Baltimore's inner-city crime and drug scene, seen through the eyes of every part of the drug "food chain", politicians, police, drug dealers and users.
Marlo finds a solution to an old problem. A familiar face joins the local school's teaching staff. Strong language/violence/sex/mature themes. (S4, ep 1)
The detail goes after some of the city's most influential people, while Herc catches the mayor in a compromising situation. Strong language/violence/sex/mature themes. (S4, ep 2)
Rawls orders a shake-up of Major Crimes, Prez is stunned by an outburst in his classroom and Royce hits back at Carcetti. Strong language/violence/sex/mature themes. (S4, ep 3)
Prop Joe attempts to forge an alliance with Marlo, Omar holds up a high-stakes card game, and Greggs and Freamon clock on in homicide. Strong language/violence. (S4, ep 4)
Marlo and Prop Joe shake on a mutually beneficial agreement, while Carcetti's campaign gets a boost at the expense of Mayor Royce. Strong language/violence. (S4, ep 5)
Carcetti responds to a vicious campaign smear, Randy makes a startling revelation and Omar finds himself in a tight spot. Strong language/violence. (S4, ep 6)
A worried Omar calls in a favour, Carcetti seeks advice from an ex-mayor and Prez begins to make headway with his students. Strong language/violence/mature themes. (S4, ep 7)
Carcetti spends time in the homicide department, while at the school Prez hits a wall and Colvin makes a breakthrough. Strong language/violence/mature themes. (S4, ep 8)
As Carcetti makes preparations to take office, good fortune finds Daniels and Omar gets out of jail. Strong language/violence/mature themes. (S4, ep 9)
Acting on Bodie's advice, Little Kevin makes a big mistake. Meanwhile, Michael goes to Marlo with a problem and Bubbles gets his own back. Strong language/violence. (S4, ep 10)
Omar surprises Proposition Joe, while the meticulous Freamon finally uncovers Marlo's gruesome secret. Strong language/violence. (S4, ep 11)
Freamon goes over his bosses' heads in his bid to find more of Marlo's bodies. Meanwhile, Michael crosses a line. Strong language/violence. (S4, ep 12)
With Burrell's help, Daniels opens up the row houses and the reality of the city's drug trade hits the headlines. Strong language/violence/mature themes. (S4, ep 13)