Stringer Bell gets an education in construction management; Bunk delivers a searing message to Omar; Daniels keeps up the front of marriage to Marla.
McNulty and Greggs embark on a road trip; Carcetti confronts a hurdle; Marlo appears to take the bait.
Brother Mouzone returns to Baltimore; Colvin puts off a reporter; Burrell delivers news to City Hall; Pearlman and Daniels plead their case.
Colvin arms himself with intelligence from Daniels' detail; Carcetti wants to fix the witness protection program; Omar struggles with dissension in the ranks.
Herc discovers a blast from the past; Omar grapples with guilt; Bunk receives a gift-wrapped surprise; McNulty tracks Terri to Washington.