At Malcolm's apartment, they see he's in wheelchair. He was at home the night of the murder, because the elevator was broken, but he tells the detectives that Kowalski was helping him get his GED. He helped him with homework, took him to ball games... he even brought him to a crime scene and let him poke a dead body with a stick. (Awwww.) Kowalski told Malcolm that everybody will want something from him; when Malcolm asked what Kowalski wanted, he said he wanted Malcolm to be good to his kids.
Back in the squadroom, Sgt. Brown is stunned that Kowalski was a Big Brother. Walsh says he had a soft spot for hard-luck kids, since he had a rough childhood himself. Banks and Delahoy get applause for solving the cat case. Alvarez comes in soaking wet, with the hose guy in cuffs. Brown gives Walsh the case back, and Alvarez has to be held back in his rage. On the computer, Cole conveniently finds a match for their eyewitness sketch of an Asian man with a scar. Leon Wu and his brother were busted by Kowalski last year. The brother died in jail, Leon got out, maybe he wanted revenge? The whole unit mobilizes, and everyone touches a bronze hat on their way out. Banks offers Delahoy a vest, but Delahoy says no. Brown says, "Let's show them what it means to kill a cop." Wait, are they going to show him how it's done?
Detectives pile out of a van, following the ESU unit upstairs. Banks starts to breathe heavy, saying he can't do this, Delahoy tells him he can get the next one and takes the lead. ESU goes in, and Banks leaves. The apartment seems empty, but Delahoy spots a fake wall and kicks it down. Entering, he spots Wu in a mirror, behind him with a shotgun; he freezes, but then shrugs, turns and is shot point-blank. Shraeger comes in next and drops him, bang bang. Delahoy is magically unharmed, and Cole sees Jesus in his haloed silhouette on wall.
Banks is puking in a trash can in the lobby. Delahoy arrives, and Banks says it sounded rough up there. Delahoy tells him that he was shot in the face. Banks laughs. As Beaumont kneels over the body of Leon, Cole comes in and tells her Brown is looking for her. When she leaves, he pulls a gun and badge out of his pocket and goes to tuck them into a hole in the wall. Just then, Walsh walks in, and Cole pretends he's just found them there. Walsh says good job. Cole, you bastard -- what have you done? Brown is outside talking to the press when Alvarez runs up and takes over. Brown doesn't argue. Walsh sits down next to a clearly upset Shraeger on a bench. She tells him not to treat her like a girl. Walsh says they found Kowalski's badge, and she did good.