Marlo maintains discipline without bringing police attention; the mayoral candidates hit different campaign trails in the final weeks of the race; McNulty turns down a promotion.
Danny and Baez investigate when an expectant mother is a victim of a "knockout game," in which teenagers punch unsuspecting civilians in the head. Meanwhile, Frank wrestles with promoting an officer.
Herc's job with the mayor takes a hard turn; Prez prepares for his first day as a teacher; Carcetti drops a bombshell on the mayor during a televised debate.
Michael proves to be adept as a runner; Rawls replaces Asher with a company man; McNulty and Bunk reminisce.
Valchek leaks details of a case to Carcetti; Royce turns against Burrell; Chris tries to enlist Michael into Marlo's ranks.
