Kima slowly recovers in the hospital. Stringer changes operations in the pit and the towers, rendering the wiretaps and clones useless, and prompting Burrell to begin dismantling the detail. Avon and Stringer meet Levy to discuss where their organization is vulnerable. Unbeknownst to the detail, Wallace returns to the pit to resume work. When Prez starts pulling political campaign finance reports, Pearlman is called to a meeting with a worried State's Attorney, and an angry Clay Davis confronts Daniels. Meanwhile, Stringer issues a difficult order to Bodie and Poot. With Shardene's help, the detail are able to install a camera in the strip club.

Due to the camera at Orlando's, the detail gather enough information to arrest Avon and many of his people, but, with Wallace dead, they are unable to bring charges against Stringer, who's left on the street. However, disgusted that Avon and Stringer had Wallace killed, D'Angelo flips on the entire organization, giving the detail more information than they could have ever hoped for. As Daniels figures out who the snitch is in the unit, Herc is shocked when he is passed over for promotion in favor of Carver, who scored lower on the sergeant's exam. In Philadelphia, Wee-Bey is arrested and gladly admits to murder after murder. Finally figuring out why Avon has been buying vacant properties in the city, Daniels, McNulty, Freamon and Pearlman take their evidence of political involvement to the FBI. Meanwhile, D'Angelo's mother, Brianna (Michael Hyatt), attempts to convince him to stand with the family.

Major Valchek gets back at Sobotka for the church gift fiasco, and a feud begins. Avon Barksdale continues to run his empire from a prison cell. On the waterfront, Port Police Officer Beatrice Russell gets stuck investigating the contraband in the The Greek's container. McNulty lends a hand with the investigation.

Trying to let go of police work and return to his marriage, McNulty gives up on identifying his Jane Doe. The detectives look into Sobotka and his money. For his union, Sobotka tries to play the political game. D'Angelo wants to live life outside of Barksdale's umbrella and Bell brings in outside help for the problem.

Greggs and Prez tap into the circuit of Russian prostitutes. With two sets of evidence, the detail goes to Pearlman who tells them neither crime merits a wiretap, but a drug connection could give the case legs. Rawls can't persuade Daniels to take the murders, but new evidence does. Though discord grows in Barksdale's empire, Bell tries to hold it together.

Bodie's disastrous sales efforts result in a tongue lashing from Stringer Bell. Ziggy pulls Johnny Fifty into a new caper that makes the Greeks pay big money. McNulty goes undercover in a brothel. As Valchek fumes over the change of targets and Burrell pulls the rug from beneath him, Daniels and Pearlman maintain their composure.

Johnny pressures Bubbles to stop snitching for the detail. Cutty lies to his grandmother about going straight. McNulty realizes pursuing Barksdale and Bell is a losing cause, so he turns his attention to nailing Kintel Williamson. Colvin's free drug dealing zone, now known in the streets as Hamsterdam, scores a small victory. Avon Barksdale emerges from prison to a warm welcome from Stringer Bell.

Major Colvin instructs his men to use brute force to get the message out to street dealers about his free zone. Avon Barksdale and Stringer Bell discover that real estate development has its own pitfalls. McNulty and Greggs ask Daniels to let them renew the Bell and Barksdale investigation. On Barksdale's orders, Cutty plans to take back corners from Marlo's crew.

Prez impresses the detail with what he's found out from Bodie's cell phone, information that sends McNulty and Greggs on a road trip. Colvin sees the benefits of his plan working. Carcetti confronts a hurdle he must clear if he wants to run for higher office, while Marlo appears to take the bait set by the Barksdale crew.

Responding to an officer's call for help, McNulty and Prez turn up the wrong alley with unanticipated results. Cutty is surprised to find help from within Baltimore's power structure for his proposed boxing gym. Omar decides to go it alone against Avon Barksdale and Stringer Bell. Bubbles is wired up and sent into Hamsterdam

Avon readies his troops for a seemingly endless war against Marlo. The detail works towards the top rungs of the Barksdale organization with the information garnered from the wire. While Royce continues to grapple with Amsterdam, Burrell offers a deal to minimize the fallout. Carcetti's political plans become obvious to his friend and fellow councilman Tony Gray. Bubbles offers his view of the world. McNulty changes tack.

With Election Day approaching, the three mayoral candidates make last-minute appeals. Carcetti wrangles for votes as he responds to a potentially devastating smear. Norris and Greggs get a lead on the Braddock case, but end up being detoured.