A traffic cop pulls over a man... and then shoots him dead. At home, Sledge is drying his hair when he gets word that the man, a criminal, was shot to death and it's the third such death in three months. At the station, District Attorney Evelyn Collins is trying to get in to see Trunk and insists on following Hammer... until she realizes he's going into the restroom. She eventually meets with an apologetic Trunk and an unrepentant Hammer comes in. Collins is investigating the murders of the criminals, each of which was killed a day after their exoneration. Drug pusher Rudy Medwick has just been released and Collins figures that he's next. Trunk orders Hammer and Doreau to cooperate with Collins and help her find Medwick.
Hammer and Doreau track Medwick to a massage parlor where the receptionist directs them to the sauna in the back. Despite Doreau's objections, Hammer goes in but Medwick doesn't want to talk to them. They're called away to the phone and the same traffic cop from earlier and his partner go into the sauna and gun Medwick down. Hammer discovers the call is a fake and goes back to the sauna where the dying Medwick tries to mime who killed him but dies before Hammer can figure it out.
Back at the station, Hammer explains to Trunk what happened and the captain talks to him in private. He's discovered that the shell casings found at the scenes of the murders belonged to cops, and dirty cops have gone vigilante. He wants Hammer to pretend to go bad and convince Doreau to sell it to the rogue cops. Hammer agrees and immediately stages a fight with Trunk where he claims to agree with the vigilantes. The two killers are in the station and see the whole thing, and think they have a new recruit. The next day, Hammer shows Trunk a note that he received requesting a meeting. When Hammer realizes the vigilantes might be watching, Hammer throws another punch which Trunk dodges. That night at his apartment, the two cops Jackson and Braddock arrive and offer him an invitation. They blindfold him and take him to the other vigilantes. After passing their test, they tell him to kill Collins to prove himself and he agrees.
At City Hall, Hammer enters Collins' office and warns her about the vigilantes. She informs her she's the next victim and he's been instructed to kill her. He pulls out her gun and prepares to shoot her, and she congratulates him on passing the test. He knew she was the leader because he smelled her perfume in the living room where he was taken, blindfolded. He loaded his gun with blanks just to be on the safe side. She lets down her hair and invites him to her place where they dance the tango and Hammer admires her gun collection. He asks if she has a list of the members but Collins is more interested in him.
When she leaves to slip into something more comfortable, Hammer searches for the list but Collins invites him upstairs. He goes up and finds her dressed as Blind Justice at her hot tub. She strips down to a swimsuit and invites him in, and points out the list on a nearby table. He draws his gun and tries to take her into custody, but she says she never trusted him and takes out a spear gun and shoots him. He dodges the spear and tries to shoot her, forgetting he loaded with blanks. Scorned, she chases him into the meeting room but Doreau arrives. She followed him, noting that he and Trunk didn't fool her. However, Jackson and Braddock arrive and Collins plans to put Hammer on trial. However, Trunk and his men arrive and take Collins and the vigilantes into custody: the captain explains he only figured out the entire thing because he lived next door and heard the gunshots. Collins asks for one last request... and punches Hammer. Hammer admits Collins was the best first date he ever had.
Later, Collins defends herself and gets off on a legal technicality, and comes to see Hammer at the station. She pulls a gun on him and shoots... and still can't hit. The officers haul her away and Hammer is happy to be proven right.