"Final Grades" is the 13th and last episode of the fourth season of the HBO original series The Wire. Written by David Simon from a story by David Simon & Ed Burns and directed by Ernest Dickerson, it originally aired on December 10, 2006. With a running time of 78 minutes, it is the second longest episode of the whole series and received critical acclaim.
Plot Homicide Sergeant Jay Landsman walks into the homicide unit office humming a carol. His Christmas spirit is rapidly dispelled when he sees several red names being added to the case board. He quizzes Detective Ed Norris about the board; Norris tells him that Lester Freamon is responsible, having received the go-ahead to search vacant houses for concealed bodies. Landsman is angry at the sudden drop in his squad clearance rate and calls Freamon a Hun, a Vandal and a Visigoth. Landsman next asks what Norris is working on and is dismayed to find out that he is also working a new case: that of a deliberate killing using poisoned narcotics. Landsman is somewhat forgiving when Norris tells him that he has the perpetrator in custody as he came in and voluntarily confessed to the crime.
Accompanied by Landsman, Norris returns to the interview room to discuss Bubbles' confession. Bubbles is distraught and is undergoing withdrawal. He vomits all over the detectives and they leave the room to clean up. When they return Bubbles has attempted to hang himself from the ceiling. The detectives cut him down.
Later, Landsman is pleased to learn that Bubbles survived. He spots Detective Crutchfield leaving the unit office and is downcast once again when he learns that Freamon has found yet another body. Landsman checks with the paramedics and then quizzes Bubbles about his actions and motives in confessing to the crime. Bubbles tells him the entire story behind Sherrod's death. Bubbles is filled with remorse and regret and pleads with Landsman to lock him up.
Landsman orders Norris to let Bubbles go. Norris worries about losing the clearance and about Bubbles's safety. Landsman tells him to send Bubbles to rehab. Later, Kima Greggs and Walon visit Bubbles at the rehab center. Walon comforts Bubbles, but Greggs cannot bring herself to go in.
Major Crimes Freamon marshals his team as they search vacant houses in the Western District. They have uncovered nine bodies so far in clusters around certain blocks. Greggs is there from homicide. Freamon remarks to her that the scary part of the investigation is that they are only searching a single sector. He telephones Colonel Cedric Daniels, who is at a staging area set up in the gym of a disused school.
Daniels answers the call, leaving ASA Rhonda Pearlman alone to field questions from Deputy Commissioner William Rawls and Commissioner Ervin Burrell. She reports that forensics teams are attending each crime scene and they are recovering 9 mm bullet casings, vacuuming for hair and fiber and laser printing for footprints. Daniels returns and is asked to confirm that the bodies are linked to one organization. He tells Burrell that Marlo Stanfield's drug organization is their prime focus and is then asked what they have on Stanfield. He explains that Major Crimes was building a case against Stanfield until three months ago when their wiretaps were pulled by Lieutenant Marimow. Burrell offers Daniels whatever support he needs. Daniels tells Burrell that he needs the patrol division to begin searching for houses. Daniels leaves to begin organizing a citywide search.
Rawls remarks to Burrell that if Daniels manages to solve this case then he will be closer to the commissioner position. Burrell tells Rawls that Daniels is a long way from his "throne" and that he is too. He taunts Rawls by saying that he made his move against him too soon. Rawls admits to the mistake and Burrell warns him never to cross him again, following their confrontation earlier in the season.
Freamon receives word from Daniels and assigns Leander Sydnor and Kenneth Dozerman to introduce the specifics of the search to the patrol division. Greggs asks what she can do and Freamon asks her to raise Sergeant Thomas "Herc" Hauk, who is currently suspended from duty pending the results of an internal investigation. Greggs finds Herc drinking in the morning and reluctant to become involved while suspended. She goads him into accompanying her by questioning whether he is police or not. She takes him to the site of his recent traffic stop of Chris Partlow and Felicia "Snoop" Pearson, as he told Freamon that he fired a nail from their nail gun into the road. They find the mark but are unable to locate the nail. Herc spends the whole time questioning why IID is investigating him when Marimow has been transferred away and Daniels had already given him a mild punishment for the incident with the minister. Tired of Herc's complaints, Greggs asks what he did in order to reassure him that he will have an easier hearing. When Herc admits the falsified paperwork and stolen camera, Greggs and her partner Bunk Moreland shake their heads in disbelief. Herc experiences further dismay, concerned that he may lose more than just his sergeant's rank.
Each patrol officer is given orders to search his post for vacant houses sealed with non-HCD materials. They are instructed to report any such houses to their sector sergeant and told that they can enter, but upon finding a body, they are not to disturb the scene further.
Daniels convenes a meeting with the detectives. Bunk and Greggs report that Herc identified the nail gun as the same one used to nail the vacant houses shut, but that they were unable to recover the nail. Freamon suggests that their next move is to seize Chris's truck and take hair and blood samples from both Chris and Snoop. Pearlman interjects, telling the detectives that they do not have the probable cause for these actions. Bunk suggests using Randy Wagstaff as a witness because he is able to link Chris and Snoop to the death of Curtis "Lex" Anderson, but Freamon insists that Randy is simply a source. Bunk becomes impatient and says that he will provide the necessary probable cause within an hour. He visits Lex's mother and pressures her into speaking up. She states that she has heard that ‘Chris’ and a girl, possibly named ‘Loop’ or ‘Snoop’, were responsible.
With their warrant - obtained with the apparently decisive hearsay input of this second source - Greggs, Freamon and Bunk perform a stop-and-search of Chris and Snoop. Greggs finds the wiring for the hidden glove box compartment and discovers a pistol concealed within. The team arrests them for the weapons charge and immediately obtains a grand jury warrant for blood and hair samples.
Back at the staging area Daniels relays the ballistics report to Freamon. The guns found in the car are clean of prints and do not match to any shootings. Freamon suggests that a trace DNA match or a witness could break the case, but that they are probably facing a lengthy investigation. Freamon asks Daniels how he chose the staging area and learns that he once went to school there.
Omar Little Omar Little and his crew divide up the spoils of their robbery. Kimmy is pleased with their success and tells Omar that she is going back into retirement. Omar's adviser, Butchie, asks how much of the shipment is left. Omar tells him that there is more than he could ever sell on his own. Butchie suggests selling it back to Proposition Joe for a profit; it is initially taken as a joke, but Renaldo and Omar begin to see the idea's potential.
Omar returns to his hideout, having met with Joe and received payment for their stolen shipment. He gives Butchie a percentage for himself and tells him that he will now act as his own bank. Omar leaves the shipment in a locked garage and calls Joe to advise him. As he leaves, Butchie warns Omar that the theft will have further repercussions.
New Day Co-Op Proposition Joe hosts a meeting with the heads of the New Day Co-Op consortium of drug dealers. He is in an awkward position, having had an entire shipment of narcotics stolen by Omar. He tries to convince his colleagues that they should pay for a replacement shipment while they work on recovering the stolen drugs. The rest of the Co-Op members are dubious and tell Joe that as the drugs were in the possession of his people when they were stolen, he will have to make up for the loss. Joe threatens to cut them off from his supplier in the future if they insist on this course and this quiets their protests. Marlo Stanfield quizzes Joe about which of his people was there when the shipment was taken. Joe admits that it was his nephew Cheese, but tells Marlo that he will protect Cheese from any retribution. He offers to put Marlo in touch with his connection so he can reassure him that Cheese did not steal the drugs for himself.
Joe discusses this course with his lieutenants Cheese and Slim Charles. Both are dubious of the wisdom in letting Marlo meet their supplier, as they believe he will try to circumvent them. Omar arrives at the store and faces hostility from Cheese and Slim Charles. Joe is more pragmatic and listens to Omar's sales pitch of returning the heroin at "twenty cents on the dollar". Cheese threatens to torture Omar, but Joe sees the futility in this and agrees to buy the drugs. Omar collects the clock that he gave Joe to fix and pays him for the work.
Joe chaperones Marlo to his meeting with Spiros "Vondas" Vondopoulos. Vondas guarantees Joe's word on the stolen shipment of drugs and leaves. Marlo instructs Monk to have Vondas followed. Monk informs Marlo that Chris and Snoop have been arrested and Marlo tells him to call their bondsman.
Dukie Duquan "Dukie" Weems walks past Randy’s home to find that it has burned down. He arrives home and overhears Michael Lee having sex with an unknown girl. He goes to attend his first day of high school, but changes his mind on the way there. Dukie visits Roland "Prez" Pryzbylewski at the middle school and gives him a gift. Prez tells him that he can stop by any time, but later sees him dealing drugs on a corner and realizes that he has dropped out of high school.
School Prez supervises his class while they take the statewide tests. Calvin refuses to begin the test, but most students are working hard. In the special class, the majority of the students are not participating, but Namond, Zenobia, and Darnell Tyson are attempting the test.
Howard "Bunny" Colvin announces the cessation of the special class to the students. The majority are pleased, but Zenobia is reluctant to return.
Prez receives the test results and is pleased to learn that over a third of his students are classified as proficient. Miss Sampson grounds him by explaining that a score of proficient means reading at a level two grades below the student's age. Prez admits that he is still learning and Sampson tells him that he is going to be fine. Prez welcomes the special students back to class. Only Albert makes a disruptive comment, but apologizes after none of the other students laugh.
Randy Sergeant Ellis Carver desperately tries to find somewhere suitable for Randy Wagstaff to stay following the firebombing of his previous home and serious injuries to his foster mother. He is insistent that Randy cannot go back to a group home. Lieutenant Mello is unsympathetic and tells Carver to take what is on offer.
Carver visits the social services offices personally and tries to convince them to put Randy at the top of the list for foster placement. Carver offers to foster Randy himself and the department tells him that he needs to go through three months of screening before he can take custody. At day's end Randy is still sleeping on the bench in Carver's office. The next morning Mello gives Carver an angry tirade when he discovers Randy and orders him to hand him over to DSS. Randy offers Carver his savings to bribe someone for a foster place.