On the drug-infested streets of West Baltimore, there are good guys and there are bad guys. Sometimes you need more than a badge to tell them apart. Season 1 follows a single sprawling drug and murder investigation in Baltimore — one that culminates in a complex series of dangerous wiretaps and surveillance.

McNulty's on harbor patrol. Daniels is in the police-archives dungeon. Prez is chafing in the suburbs. Greggs has a desk job. The detail may be on ice, but corruption marches on . . . and a horrific discovery is about to turn the Baltimore shipping port inside out. Setting up in the wake of the first season's joint homicide/narcotics detail that exposed a major drug operation — and left its members stigmatized and reassigned — the second season expands to include not only familiar drug dealers, but a group of longshoremen and organized crime members who are caught up in a major homicide case.

The heat is on in Baltimore. The drug war is being lost, bodies are piling up, and a desperate mayor wants the tide turned before the election. But the police department hasn't got any answers. Wiretaps haven’t worked. Neither have stakeouts or street busts. With the demolition of the Franklin Terrace towers, Stringer Bell and the Barksdale crew have been forced to improvise. But no matter how hard McNulty and the detail try, the dealers always seem to be one step ahead of the game. It’s time to change the rules.

In the projects. On the docks. In City Hall. And now, in the schools. The places and faces change, but the game remains the same. A new story begins. This year, while expanding on storylines introduced in previous seasons — including the new vocations of several characters, the rise of a new drug empire, and the city's imminent mayoral election — the series expands its focus into Baltimore's school system, providing an inside look at the role of the urban educational system in shaping young people's lives. This storyline is played out through four new young characters, each of whom faces difficult choices amidst the temptation of crime and easy money.

In the projects. On the docks. In City Hall. In the schools. And now, in the media. The places and faces change, but the game remains the same. In the fifth — and final — season, the series expands its focus into the media — specifically the role of newspapers in big-city bureaucracy — as it follows a newspaper staff as they struggle to maintain integrity and meet deadlines in the face of budget cuts and staff reductions.