In the Season Four premiere, four boys from West Baltimore--Michael, Namond, Randy and Dukie--play out their summer vacation in the streets as the fall school semester approaches. Having failed to capture a potentially valuable homing pigeon, the boys are stirred to action when Dukie is beaten up, and Randy concocts a retaliation plan against the rival gang. The action is slower at Bodie's corner, giving young Namond an excuse to take off early from his "summer job" as a runner. Meanwhile, Marlo has solved the problem that baffled Stringer Bell: how to maintain discipline--read: murders--without getting police attention. At the detail's office, Freamon and Sydnor press Pearlman to issue City Hall subpoenas, while Daniels's replacement, James Asher, surveys the blueprints to his dream house. With the mayoral race heading into its final weeks, Mayor Royce and his primary challenger, Tommy Carcetti, hit decidedly different campaign trails. Carcetti's deputy campaign manager, Norman Wilson, and his campaign guru,

With his lead dwindling in the polls, Royce resorts to extreme measures to stall Carcetti's momentum. At Bodie's corner, Michael proves adept as a runner, with both Bodie and Marlo taking notice. A re-up bodega is put under surveillance by Omar and Greggs, for different reasons. Rawls replaces Asher with a 'company man,' Charles Marimow, who pushes a new agenda on the detail, to Freamon and Greggs's dismay. A domesticated McNulty invites Bunk over for dinner, which ends with the two remembering the good old days at a familiar spot. Randy enjoys a productive first day at school, though Prez, the new teacher, isn't so fortunate. Herc reaps an unexpected benefit, courtesy of the mayor. Colvin contemplates trading his new job in the private sector for one that gets him back on the streets.

On the trail of missing bodies, Freamon turns to a higher authority after being rebuked by Landsman. Carcetti finds his erstwhile promises of prosperity undermined by the school debt, forcing him to contemplate groveling before the Governor in Annapolis. Colvin approaches a pair of familiar faces--Deacon and Watkins--to keep his experimental class funded. Bubbles considers taking extreme measures to rid himself of his nemesis. Prez is rankled by Dukie's academic promotion; Marimow gets his walking papers; Omar orchestrates another big sting; Namond and Cutty get a first-hand taste of the 'new' Michael; and Carver's promise to look out for Randy ends up looking empty.

To monitor the pulse on the street, Carcetti makes the rounds with members of the force. With Marimow on his case, Herc resorts to strong-arm tactics to retrieve his pinched camera, but Marlo isn't impressed. While Proposition Joe shows off his vocal range, Chris shows Snoop how to expose, and dispose of, New York infiltrators. At school, Prez struggles to fit a test-practice mandate into his curriculum, and Colvin figures out a way to involve Namond and other 'corner boys' in problem-solving. Not buying into Old Face Andre's account of a homicide, Bunk tries to convert Holley and Crutchfield to his way of thinking. A newly sober McNulty attends an Irish cop's wake--with a not-so-sober Bunk. Daniels gains the mayor's confidence, while Rawls confirms Burrell's suspicions of collusion. Randy finds himself on a short leash; Dukie learns that computer skills breed popularity; and Michael is dismayed by the unexpected return of a missing family member.

Acting on Clay Davis's advice, Burrell seeks to burnish his reputation by ordering the department to double the number of street arrests. The mandate does not sit well with McNulty, who sets his sights instead on cracking a string of church robberies. Later, Davis shows he can play both sides of the political fence by making Carcetti an offer with long-term benefits for both. As the weather turns cold, school officials turn up the heat in Prez's classroom, and make it clear to Colvin that there are no exceptions to certain rules. After being apprehended, interrogated and released, Kevin is advised by Bodie to come clean about the incident to Marlo. Betrayed again by Herc, Bubbles decides to get even with the unwitting help of a local minister. Busted by Carver, Namond spends the night in the precinct, then is released to Colvin's home, where he proves, surprisingly, an exemplary guest. Donut's latest joyride ends badly; Randy is stigmatized at school; Chris takes care of Michael's problem.