Detective Jimmy McNulty (Dominic West) investigates a drug dealing organisation led by the elusive Avon Barksdale (Wood Harris). McNulty patiently scrutinises Barksdale's dealings until he has enough evidence to trap him.
Blue-collar workers at the city port get caught up in smuggling drugs and other contraband.
The focus switches to the actions of local politicians and the fledgling drug-dealing Stanfield group.
Baltimore's school system takes centre stage.