In the pilot episode of this highly realistic drama series, Baltimore homicide detective Jimmy McNulty gets into hot water and winds up assigned to a detail of narcotics outcasts charged with investigating drug lord Avon Barksdale and his powerful operation in Franklin Terrace. Meanwhile, Avon's nephew D'Angelo is fresh off beating a murder rap, but he finds himself 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 (chess) and later impresses Bell with his 'take' from the low-rises.

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.

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.

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.