Upon the demolition of tower 221 as a part of a new strategy to fight crime, Barksdale’s men look for another place to run their operations. McNulty contemplates entrapping Stringer Bell and Proposition Joe through the wire.
As McNulty has suspicions about D’Angelo Barksdale's suicide, he takes it upon himself to investigate the matter. Omar resumes robbing the Barksdale stash houses. The Major Case Unit decides to arrest lieutenant Cheese, revealing their wiretap in doing so.
Omar robs another Barksdale stash house, resulting in a fatal confrontation. McNulty seeks Bunk’s opinion on D’Angelo’s death, and refuses to give up the Barksdale case.
Cutty joins the Barksdale Organization as he gives up on straight work, while Avon is granted parole. As McNulty visits Bell’s community college, he learns of his attempt to establish a legitimate property development business.
Bell attends a party thrown to celebrate Avon’s parole. McNulty puts off his pursuit of Stringer Bell for a while. Omar and his crew prepare for their next raid.
Bell and Avon are troubled by the rapid rise of the costs of their property development businesses. Daniels refuses to let McNulty and Greggs investigate Bell.
When Daniels finds out that his unit got reassigned, he has a heated argument with an unapologetic McNulty. Bell learns that Brianna wants to talk to McNulty about D’Angelo’s death. Freamon identifies a Barksdale communication network by analyzing call patterns.
McNulty meets with Brianna. Prez manages to find the store that sold Bodie’s disposable phone, whereupon McNulty and Greggs set out to track the buyer of the phones. It’s revealed that Bell planned D’Angelo’s murder.
Prez shots another officer by mistake. Omar vows revenge on Barksdale after the attack on his grandmother.
As Brother Mouzone returns to Baltimore seeking revenge, he decides to look up Omar. Avon refuses the proposal of a truce after Marlo murdered Devonne. Following the wiretaps mishap, Freamon arranges to supply the Barksdale Organization with pre-wiretapped phones.
The Unit gets on tape incriminating evidence against Stringer, who tries to get Avon back in prison. Omar joins forces with Brother Mouzone, and as they learn Stringer’s whereabouts from Avon, they find him and kill him.
Avon continues his war against Marlo. The press find out about what happened in Hamsterdam, resulting in a fierce attack on Royce. Although disappointed by Stringer’s death before he could arrest him, McNulty uses the information he provided through the wire to arrest Avon.