Durante o julgamento de D'Angelo Barksdale, um traficante de nível intermédio acusado de assassinato, a testemunha principal da acusação volta atrás no seu testemunho, resultando num veredicto de inocente. Após o julgamento, o Detetive McNulty explica ao Juiz Phelan que considera o grupo de Barksdale como os suspeitos de uma série de assassinatos relacionados. Quando o juiz contacta os superiores de McNulty acerca desta revelação, McNulty é repreendido pela sua indiscrição. Entretanto, D'Angelo está livre para voltar ao trabalho, mas descobre que foi despromovido para o nível de vendas de rua.

'You cannot lose if you do not play.' - Marla Daniels.

McNulty feels the heat when a witness who testified against D'Angelo is found murdered. Meanwhile, Greggs is given the lay of the land regarding Avon Barksdale's key players, and Herc, Carver and Prez find big-time trouble at the towers.

"It's a thin line 'tween heaven and here." - Bubbles.

Greggs and McNulty try to get Hardcase to turn informant as arraignment begins for those caught in the raid. Barksdale places a bounty on the head of rival gang leader Omar. Meanwhile, McNulty takes Bubbles on a cultural field trip, and Herc and Carver try to track down Bodie.

"..a little slow, a little late." - Avon Barksdale.

McNulty's detail finally gets 'clone' pagers to track Barksdale and his gang, but nobody can crack the codes used by the callers. Meanwhile, Bell instructs D'Angelo on how to school his lookouts while simultaneously flushing out a possible snitch. Later, Carver and Herc find Bodie, but their interrogation doesn't turn up results.

"..and all the pieces matter." - Freamon.

When Rawls looks to make a premature arrest for three murders that are linked to D'Angelo and Avon Barksdale, McNulty and Greggs must argue for a delay in order to preserve the valuable wiretap gains they have made. Meanwhile, Wallace and D'Angelo struggle with their consciences after Avon pays them blood money.

"A man must have a code." - Bunk.

Tipped off by the wire, Greggs, Herc, Carver and Freamon make a bust, but the incident makes Avon and Stringer suspicious, leading them to close shop in the Pit. Meanwhile, Bunk and McNulty look for another witness in the Gant slaying and hunt a suspect known as 'Mr. Bird.'

"Come at the king, you best not miss." - Omar.

An unlikely source gives McNulty the tag of a car driven by Stringer Bell. Meanwhile, Greggs and Carver bust a congressional aide carrying dirty cash, but are forced to let him go. Omar earns his 'loose cannon' moniker.

"Maybe we won." - Herc.

Barksdale plays an expensive game of one-upmanship with an east-side rival. Meanwhile, Herc and Carver take some cash off of Wee-Bey's hands, and Omar resurfaces with a bang.

"And then he dropped the bracelets..." - Greggs.

With Wallace in custody, McNulty and Daniels try to figure out what to do with him in the months before he testifies. Sydnor and Carver track down one of Barksdale's stash houses, and Prez shows off his 'gift for the paper trail.' McNulty's estranged wife Elena takes desperate measures after learning that he had their kids follow Stringer Bell.

"Dope on the damn table." - Daniels.

The police turn up the heat on tracking down Savino, Wee-Bey and Little Man. Burrell orders Daniels to hit drug dealers for results that will impress the press. Barksdale sees his ranks thinning after the hit on Orlando. Bubbles tries to stay sober while scoping out the projects for McNulty; and Freamon determines there's a rat in the detail.

"This is me, yo, right here." - Wallace.

The low-rise pay phones are out of service, so McNulty and Daniels try to keep pace by tapping Barksdale's office. Bodie gets new responsibilities from Stringer; Freamon gives Shardene a 'new look'; and D'Angelo goes to NYC on an errand for his uncle. With the detail's future hanging in the balance, Daniels faces off against Burrell and his political allies.

"all in the game..." - Traditional West Baltimore.

Every crew has weak links--including Avon Barksdale's. With the heat turned up in the high-rises, Daniels and McNulty turn to a higher authority in an effort to crack the case wide open. Season finale.