Assistant D.A. Allyson Russo is waiting on an isolated bridge when someone pulls up in a car on the opposite side. The passenger has his enforcer, Frank Murphy, get out. Allyson demands that the passenger come out in person to give her the evidence that she's there for. Armed men emerge from the woods and Murphy fires a few shots, but is his. He manages to drive away with his passenger. Allyson gets into her car and backs away, knocking down one masked man.
Allyson explains to Winston that she's been working the Westland Gang case and has no idea who the shooters or how they found the meet with her confidential informant. Someone has been going through her apartment and her car, and she's had a police detail assigned to watch her. She wants someone on the job who will find out who is after her. Winston starts to introduce Chance but realizes that he's not there. He goes to find Chance upstairs watching TV, and explains that Allyson could put them in contact with a lot more customers. He convinces Chance to come down and makes introductions, and then explains they'll make Allyson look vulnerable to expose the threat. She's more interested in knowing why Chance is the best. Chance ducks the question and wants to know who her confidential source is, and warns that he needs to know who it is to identify her problem and get her out of trouble. Allyson explains that her contact is Whitey Doyle, who led the Westland Gang for 20 years and then disappeared 10 years ago. Allyson has no idea why he's decided to provide her with evidence. Chance wonders why Doyle picked her, and Allyson figures that he came to her because she's going after the Westland gang. He tells her that she's screwed... and he'll take the case.
Chance tells Allyson he's going to set up a second meet with Whitey, which will lure out Allyson's killers. He then goes to see Allyson at the DA's office, claiming to be Doyle's lawyer, and starts negotiating a second meeting. Allyson's supervisor, Harris, insists that he be in on any meetings. Chance refuses, noting the DA's office is filled with leaks. When Harris demands to know how Whitey's request for immunity is going to hold up, a surprised Allyson listens as Chance cites legal cases to him. Afterward, Allyson talks to Chance and wonders if he's a lawyer. Winston calls and passes on some information, and Chance tells Allyson that there's someone crooked involved: Allyson, who had $50,000 turn up in her checking account during her investigation of a racketeering case. Allyson insists she isn't on the take and Chance reluctantly accepts her protestations.
Inspector Gibson and his men take Allyson and Chance to the meeting with Whitey. As they go, Gibson suggests that she shouldn't meet with Doyle alone. Allyson agrees but notes they don't have a choice. When Gibson suggests everything would have been over if he had been there, Chance presses him for details and Gibson explains that they could have checked the bridge. Chance points out that Allyson didn't say the meeting took place on a bridge. He then lunges forward and attacks Gibson's partner. They struggle as the car goes out of control. Chance shoves the driver out while Gibson draws his gun and opens fire on Chance. While they hang out the door, Allyson grabs the wheel and tries to keep them from crashing. They plow through traffic until Chance flips Gibson out, gets back up, and takes control of the car.
Once they pull over and Chance steals a new car, Allyson wonder why Gibson tried to kill her. As she prepares to call her office, Chance finds a tracking unit in the trunk of Gibson's car. Gibson's men arrive and Chance gets her out of there. He shows her the tracker and explains that they're using her to get to Whitey, and now they're following them in the hopes she'll go to Whitey. When Chance says to start removing things that could contain the tracker, Allyson misunderstands her and tosses her phone out. That doesn't work and he tells her to start removing clothing. Chance figures that the police can't be trusted and calls Winston to brief him on the situation and call his friend in Internal Affairs.
Allyson removes all of her clothing but the tracker still points to her. He realizes that the tracker is inside of her and says he can find someone to remove it. However, they have to lose Gibson first. Chance drives through a red light at the last second and manages to lose Gibson temporarily.
Chance arranges to pick up Guerrero, who wonders why Allyson isn't naked yet. They explain that they already tried that and then Guerrero gets in the back with her.
Winston meets with his old friend from IA, Detective Al Jenkins, and tells him what's going on. When Jenkins hears that Gibson and Doyle are involved, he warns Winston that Doyle had Gibson and his men on his payroll. Gibson is a star in the department and nobody wants to believe the worst of him. Worse, they have evidence that Allyson was taking bribes repeatedly from Doyle, and Doyle had a ledger with all the people on his payroll. Jenkins doesn't want to help a crooked ADA and walks away.
Guerrero gets a scalpel out of his bag and prepares to cut Allyson open. Chance convinces him to hold off on the cutting for now. He scans Allyson and locates the tracker in her stomach, and says he knows a guy who can jam the signal. Chance drops him off to find his man, and then calls Winston. Winston tells him what he learned and warns that someone repeatedly tried to put money into Allyson's case, and she kept returning it. Chance decides they need to find Doyle, and explains that Doyle must have a connection to Allyson. She finally admits that Doyle is her father.
As Gibson and his men close in, Allyson explains that Doyle left her mother when she was two, and they never talked about him again. Chance says that they have to meet Doyle and have him testify against Gibson. Doyle has a doctor who treats his men, and Chance figures that's the best place to start looking for Murphy. He pulls down an alleyway and stops, and then opens fire on Gibson's men, shooting out their tires before running away.
Winston calls Jenkins and explains that Allyson is Doyle's daughter, not crooked. He needs Jenkins' help, and reminds him that he quit the force because he wanted to do what was right, and wants Jenkins there with him. Jenkins tells Winston to get Allyson to the courthouse. Meanwhile, he'll call in Judge Heard, who he knows is honest, and have her hear the case against Gibson.
Chance and Allyson catch a taxi. She explains that her mother had lymphoma and Doyle put money in her checking account to cover the expenses. She returned the money every time and went into debt rather than take money from Doyle.
Guerrero goes to an electronic store and meets with Omar, who is removing a house arrest device from a crook, Scar. When he objects, Guerrero shocks him and asks Omar for information on jamming the transmission. Omar points out that a microwave oven could scramble the signal.
At the hospital, Chance checks patients with potential gunshot wounds and finds Murphy. Allyson asks where she can find Doyle and Murphy reluctantly makes a call. Allyson gets on the phone and tells Doyle that he might get burned, but he owes her and all he needs to do is messenger the ledger to the courthouse. Murphy takes the phone and makes arrangements to have the ledger sent to her office at the courthouse. As they leave, Murphy asks for Chance's gun, saying he knew he wouldn't get out alive and he's always protected the Doyle family... including Allyson. As Chance and Allyson go down the fire escape, one of Gibson's crooked cops bursts in and Murphy shoots him.
Jenkins and his men arrive at the hospital to arrest Gibson, who has been caught in Murphy's room. When Gibson warns that he doesn't know what he's getting into, Jenkins insists the people named in the ledger have a debt to pay and he doesn't care who they are. Gibson says that maybe he should care... and one of Jenkins' men in Gibson's pay shoots Jenkins.
Guerrero goes to the office and explains to Winston that they can jam the GPS tracker with a larger microwave generator. They just need one set to the proper frequency, and Guerrero has an idea.
As they head for the courthouse in a stolen ambulance, Allyson wonders why Murphy would have sacrificed himself for her. She notes that Doyle walked out on his family, but Chance suggests he did it to keep his wife and daughter safe. He admits he can appreciate Doyle's dilemma. Winston calls and tells him that Jenkins is dead and can't escort them in. Gibson pinned the murder on Allyson, and has surrounded the courthouse to stop her. Chance asks for a minute and explains to Allyson that crooked cops all over town are looking for her, and there's no chance of running. She realizes that he's right and Chance talks to Guerrero.
The police at the courthouse spot the ambulance coming and open fire. It doesn't stop and it crashes into the barricades. They open the door and find that Chance has rigged the ambulance well and accelerator.
Chance and Allyson approach the courthouse on foot and he asks her to trust him. She does and they go inside and then split up. Gibson uses the tracker to close in on her as she goes to see Judge Heard.
Gibson and his men follow the signal into a storage area, unaware that Chance is hiding nearby. The crooked cops follow the signal to a file cabinet. Inside is a tracker set to emit the same frequency as the tracker. Chance attacks Gibson and the two struggle. When one of Gibson's men rushes over, Chance's uses Gibson's gun to shoot him while the other man tries to get a clear shot. Chance shoves him into a case but Gibson produces an extendible baton and attacks him. When Chance disarms him, Gibson runs away before Chance can capture him.
Allyson explains everything to Heard, who tells her that the ledger is in the judge's chambers... along with Doyle, who delivered it. He greets Allyson and tells her that her problems are over. When she points out he'll go to jail, Doyle explains he did it because his little girl was in danger. He admits that he's crook and a thug, but until there's an accounting, he'll never be a father. Chance calls from outside and tells her that she doesn't need to run. She wonders if he will, and Chance just turns and walks away.
Later, Allyson visits Winston and Chance and says that there have been over 60 arrests. However, they haven't found Gibson yet. When she wonders what she owes them, Winston says that it's been taken care of by Doyle. She admits that she's worried that Gibson will come after him. Winston explains that Chance doesn't like loose ends. She asks him exactly what Chance is, and Winston isn't sure what to say.
Gibson slips into a hotel and finds Chance waiting for him... with the baton.