Baltimore homicide detective Jimmy McNulty gets into hot water and winds up assigned to a detail of narcotics outcasts investigating drug lord Avon Barksdale. Meanwhile, Avon's nephew D'Angelo, fresh off beating a murder rap, is demoted upon his return to the gang.

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.

The early-morning 'field interviews' by Herc, Carver and Prez result in a minor riot, a boy losing an eye, and some bad publicity for the department. On the other side of the law, D'Angelo teaches Wallace and Bodie how to play the game... of chess.

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

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.

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

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 new suspect.

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. Later, Omar justifies his reputation as a 'loose cannon'.

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.

With Wallace in custody, McNulty and Daniels try to figure out what to do with him in the months before he testifies. Meanwhile, Sydnor and Carver track down one of Barksdale's stash houses, and Prez shows off his 'gift for the paper trail'.

The police turn up the heat on tracking down Savino, Wee-Bey and Little Man. Meanwhile, Burrell orders Daniels to hit drug dealers for results that will impress the press; Barksdale sees his ranks thinning after the hit on Orlando, and Bubbles tries to stay sober.

The low-rise pay phones are out of service so McNulty and Daniels try to keep pace by tapping Barksdale's office. Meanwhile, Bodie gets some new responsibilities from Stringer, Freamon gives Shardene a 'new look', and D'Angelo goes to NYC on an errand for his uncle.

It transpires that 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.