Series Finale:     
Episode 20 — Partners
A waitress alerts Jack and Dan to a dine-and-dasher, so Dan jumps through the restaurant’s window and gives chase. Jack follows, but he collides with a man exiting a doorway, and the culprit outruns Dan.

When newly promoted Deputy Chief George Jenkins tours the station, Jack hides his face, telling Dan that Jenkins was his first partner and that they were rivals for Liz’s affection, but Jack won her heart. However Jenkins sees Jack and suggests they meet for beers. Dan immediately dislikes Jenkins.

Back at the restaurant, Jack and Dan ask the waitress to describe the dine-and-dasher to Samantha, who’s been enlisted as their sketch artist. Then Jack notices a nearby ATM, noting the security camera inside might’ve caught the culprit on video. Dan believes that there’s something bigger going on. Jack doesn’t.

Meanwhile, mobster Jimmy Nichols greets a man named Mick. When Jimmy discovers Assistant D.A. Liz’s recently dialed number on Mick’s cellphone, he kills him for being an informant.

As Jack and Jenkins catch up over beers, Dan interrupts: his old partner, Frank Savage, just told him that the “Savage & Stark” TV movie about their saving the governor’s son in 1985 will be re-released and the Dallas Museum of Cultural History will be screening the film.

Later, Jack drops off Jenkins, who finds Nichols inside his house. Nichols reminds Jenkins that he’s been in his pocket for ten years—and he demands that Jenkins pin Mick’s murder on someone.

Jack asks Liz to subpoena the ATM camera footage, but she puts him off. Liz then tells Lt. Ruiz that an informant—who already said someone on the force is working for Nichols—didn’t show up for a scheduled meeting last night.

When Jack and Dan show snitch Julius the sketch Samantha drew, he notices an eyebrow scar, and he I.D.’s him as numbers runner Phil Nicks.

Meanwhile, Jenkins holds up a bloody gun he found next to Mick’s body—which has been moved across town—and orders tests to determine the time of death.

Liz sees the police photo of Mick’s body and tells Ruiz that he was her informant. Ruiz says that Phil Nicks is already a suspect.

As Jack and Dan arrive at Nicks’ home, so does Jenkins. Backed by carloads of officers, he makes the arrest.

At the station, Jack and Dan watch Jenkins telling TV reporters about the arrest, claiming that the murder took place at 1:30 p.m. on Tuesday. Jack notes that’s when they were chasing Nicks and wonders if Jenkins arrested the wrong guy. Dan tells Jack to trust his gut. Then Frank arrives to take Dan to their movie’s screening.

After Liz tells Jenkins about her informant’s murder, Jack sees Jenkins showing Liz the door. Jack tells Jenkins that he’s caught the wrong guy, which Jenkins denies.

When the audience for the screening howls with laughter, Frank and Dan angrily exit the theater, get drunk, and destroy the exhibit’s “Oddities of the ’80s” sign, which gets them thrown into the county jail.

Meanwhile, Samantha tells Jack that she hacked into the ATM system; she shows him the video footage, which reveals the scar-faced Nicks. When Jack calls Jenkins about the video footage, Nichols is at Jenkins’ home and orders Nicks—who’s also in county jail—killed immediately.

When Dan and Frank awaken in jail, a cellmate says that they missed the excitement,—another prisoner is dead—and claims that Nichols ordered the murder.

Meanwhile, Liz tells Jack that Nicks hung himself in jail and left a note confessing to Mick’s murder. Case closed.

And when Nichols tells Jenkins that he’s concerned about a D.A. knowing there’s a dirty cop on the force, Jenkins says that Nicks is dead, so the case is closed. Besides, cops don’t like extra work.

But Samantha did some. She tells Jack that she discovered a DNA preservative that’s used in the police lab in the blood on the gun found at Mick’s murder scene; that means the blood was stolen from the lab. When Jack tells Jenkins about the stolen blood, Jenkins asks him to keep it between us—and he loads a pistol.

When Liz picks up Frank and Dan from jail, Dan commandeers Liz’s car and races them to the station. Meanwhile, Jenkins goes to the lab, asks Samantha to leave, and aims his gun at Jack, who realizes that Jenkins is the dirty cop. Jenkins asks Jack to join him in working for Nichols at double his salary. Jack agrees, they hug, and Jack knocks Jenkins’ gun aside. They exchange punches, and Jack grabs the gun. But he’s distracted by Samantha’s return, and Jenkins floors him, then aims the gun at Samantha.

Jenkins orders Samantha and Jack to kiss, thereby exchanging DNA. He plans to frame Jack as the dirty cop who was having an affair with Samantha—and killed her when she caught him stealing evidence, then killed himself. Jenkins sends Liz an email from Samantha’s cellphone supporting this lie.

When Liz gets Samantha’s email, Dan doesn’t buy it, and he and Frank head for the lab, where they repeat the dialogue and action from their movie: breaking a window, drawing Jenkins’ fire until he’s out of ammo. He reloads, takes Samantha hostage, and forces Dan and Frank to drop their weapons. Then Jack decks Jenkins from behind.

Afterward, Ruiz congratulates Dan, Jack, and Frank, who say goodbye. Then Jack and Dan speed off to investigate a stolen toaster.
First aired: December 10, 2010.