While cleaning up the evidence room, Stark lectures Bailey: "No evidence ever solved a case from inside a plastic baggy." Liz's mom, Helen, is at the precinct. She tells the detectives about her stolen Cutlass. Bailey tries to downplay the crime, but Stark assures Helen that their first priority is making sure "you and the people you love are safe."
After lifting a pair of brass knuckles from the evidence room, Stark says that when they solve the case, Helen will serve Liz up to Jack on a silver platter. That way they can hang out in the back of their car, listening to Foghat.
Meanwhile, Eric Williams is arguing with his brother, Keith, about selling guns to the Guatemalans, because Guatemalans killed their brother. But it wasn't "these Guatemalans," Keith explains, saying he plans to sell the guns to Osvaldo, who lets the brothers know that his nephew will be in touch.
The detectives are investigating Helen's yard. Bailey thinks it's kids who stole the Cutlass. Dan disagrees, pulling a submachine gun out of the bushes. It's revealed, however, that Stark didn't take the brass knuckles; he took the machine gun.
The prints on the gun lead the detectives to Russell and his brothers. Eric and Keith both explain that Russell died. Bailey doesn't buy it, because the gun they found has Russell's prints on it.
A car arrives and the driver, upon seeing the detectives, pulls back out and takes off. Stark and Bailey, believing Russell is driving, follow in hot pursuit. Stark shoots the tires of the other car, and the perp starts running on foot, but Bailey's too fast for him. Bailey and Stark are distressed to learn that the hooded perp they were chasing is not Russell.
Keith calls the Guatemalans because the cops just busted the broker's nephew. Eric tries to persuade Keith to forget the deal since he thinks Russell is alive. Keith doesn't believe that and continues to work on the deal. Eric decides he's going to find their brother.
Meanwhile, Osvaldo believes that the Williams brothers have set him up because his nephew was arrested. Denying the accusation, Keith agrees to kill the cops.
Stark tells Bailey go to see Russell Williams' ex-girlfriend. She explains that Russell is dead but agrees to give the detectives whatever she still has of Russell's.
The two girls who had actually stolen the Cutlass and drive past an unknowing Bailey, who's waiting for Stark to come back with Russell's stuff. Stark returns, and Bailey tells him Stark lifted the evidence. Stark defends his actions "because I am a cop. I saw a case gathering dust for four years in that closet, and I knew that we could crack it."
Elsewhere, Eric finds the Cutlass, kicks the girl and her boyfriend out, and starts searching for any clue as to Russell's whereabouts. He finds Helen's address in it and drives off.
Keith has been outside of the precinct all day, waiting for the detectives to leave the station. Inside the precinct, Bailey is speaking with Liz about Stark's questionable police work. He asks her to get the evidence they have on the gun ring. Liz agrees, hoping that her mother will be fine. Bailey assures her that this case didn't actually have anything to do with Helen. As he tells her this, Eric shows up at Helen's house.
Bailey and Stark arrive at a storage facility, still arguing about Stark's actions. They go to Box 128. Inside, the detectives find guns and Russell's body.
Keith arrives and starts shooting. He shoots at a box of explosives, blowing it up. He calls Eric, who is still at Helen's house and tells him not to worry about the cops. Stark and Bailey, however, have jumped into smaller storage cases within Box 128 to keep safe from the explosion.
Liz calls Bailey to thank him for returning her mother's car but is cut off by Eric, who's now holding both mother and daughter hostage.
Realizing they didn't find the Cutlass, the detectives head to Helen's house.
Keith lets Osvaldo know that the cops are dead and it's time to close the deal. Keith is waiting at Helen's house as well.
The detectives arrive at Helen's. When Eric and Keith answer the door, everyone is shocked. Keith starts shooting, and the detectives take cover behind the Cutlass. Bailey tells them that they found Russell's ring. Keith tells Eric that he accidentally shot Russell. Eric rushes Keith, and the brothers are now fighting each other.
Knowing the layout of the house, Bailey moves around to the back. After knocking Keith out, Eric turns his attention back to Bailey and now has his gun on the detective and the hostages. Bailey tries to talk to Eric. Although he ran out of bullets, Stark still has his partner's back: he drives the Cutlass into the house, hitting Eric in the process.
Osvaldo arrives, and after seeing the havoc, decides the deal's off and drives away.
Ruiz commends the detectives on their work, but she orders Stark to never go near the evidence room again. Bailey tries to apologize to Liz but passes out from a concussion he sustained during the mayhem. He wakes up in the back of Stark's car with his head in Liz's lap. Stark puts in his Foghat tape and drives off.