A man named Kohl arrives in New York, using the alias Wallace Nagel, and two men discuss him and figure that he knows everything.
Kohl makes his way off of the train and sees a man with a photo looking for him. He quickly ducks away.
At the library, Reese brings Finch a cup of green tea. Finch is momentarily concerned that Reese is trying to find out more about him, and then tells him that their new number is for Wallace Nagel. Nagel immigrated to the U.S. from Germany and worked in international export. Reese checks the dates and notices that Nagel hasn't made any electronic transactions in 24 years, when he disappeared in 1987. He figures that Nagel is an alias and Finch tells him that the man purchased a cemetery lot in 1987 just before he disappeared.
Finch then goes to see someone with pre-digital information to dig up data on Kohl. He meets with a book dealer, Pilcher, and warns the man that he knows about his illicit sale of Soviet submarine schematics. Finch wants explicit information in return for his silence, and Pilcher closes up his shop.
Reese goes to the cemetery and discovers a recently excavated grave. He finds a coin in the dirt.
Pilcher explains that the East German Stasi kept detailed surveillance files on everyone, and confirms that "Nagel" is actually Ulrich Kohl. Kohl was part of a Stasi espionage team that traveled the world hunting down and neutralizing East German defectors. As Finch leaves, he admits that he knew about the submarine schematics because he's a sucker for surveillance.
Back at the library, Finch goes over the files and calls to tell Reese that Kohl was in East Germany when the Berlin Wall fell. American authorities hunted him and Kohl hid in the Soviet Union, taking his wife Anja with him. She was killed in a car accident in 1987, and Kohl disappeared in 1989 when East Germany collapsed. Reese explains that there was a buried stash kit in Nagel's grave, and figures there was money and weapons in it. The two men figure that Kohl the spy is back.
An armed Kohl goes to an apartment and confronts a man named Hauffe. Hauffe has no idea who Kohl is until Kohl shows him a photo of his dead wife Anja. Kohl then shoots Hauffe in the shoulder, tells him they have something to discuss, and enters the apartment.
In Europe, Reese meets with his contact, Stanton, who tells him to have a drink and relax. She says that she'll have to pick a new name for him, and then warns him that in his new line of work, there's no way to go back. Stanton then asks if he saw any old friends when he flew over. When Reese said that he didn't, Stanton shows him a photo of his meeting with Jessica Arndt at the airport as he left the U.S.
Finch checks the coin from the grave and confirms that it's an East German mark and out of circulation since 1990. He's traced a sale of the coins to a rare coin store and confirmed that Kohl was the seller. Kohl made a call and traced the address, and Finch sends Reese there. Reese finds Hauffe's corpse and realizes that Kohl called to make sure that Hauffe was home. He finds interrogation marks while Finch checks the files and confirms that Kohl worked with three other men: Steiller, the team leader; Wernick, a document forger; and their case officer, Heinrich Hauffe. Reese figures that Hauffe was a defector and then notices a hidden compartment. The contents confirm that the dead man is Hauffe, and they realize that Kohl is killing his teammates.
The man from the station comes up behind Reese and holds him at gunpoint. Reese disarms him and knocks him out, and confirms that the man is with German Intelligence. Reese calls Fusco and tells him about the shooting and tells him to interrogate the agent when he comes to investigate the shots. Reese then fires his gun and leaves with the agent's encrypted phone. The last call, unencrypted, was to Wernick, who is working as a Wall Street lawyer under an alias. Reese figures that Kohl is after revenge, possibly for Anja's death, and figures that it was a staged accident.
Kohl goes to a café and hits Wernick with a poisoned needle as the latter eats his meal. He then sits across the table from his teammate and assures Wernick that it's something fast. Kohl then explains that he has the information that Hauffe kept, and shows him a photo of Anja. He says that he promised to keep Anja safe, and says that he paid for his sins and the team's. When he was imprisoned, he never stopped planning his revenge. Wernick admits that he tried to forget everything and admits that what they did was wrong. As he dies from the poison, Wernick tells him to be at peace and collapses.
Finch has traced Wernick's location from his assistant, and Reese arrives there just in time to see Wernick go down. Once the EMTs load Wernick in the ambulance, Reese steals it and drives away. He finally pulls over and says that he can save Wernick in return for information. Wernick explains that they were taking out American informants, and that the rest of the team traded Kohl to the Americans in return for new lives. When they defected, the Americans went after Kohl and Anja, staging the car accident. Reese gives him the antidote but Wernick passes out before he can give him Steiller's location.
Reese passes on the information from a pin that he found at Hauffe's apartment, and Finch confirms that belongs to a German-American society for New York citizens of German descent. Finch figures that Steiller was also a member.
Fusco and Carter confirm that Reese stole the ambulance, and then interrogate the German Intelligence agent, Heinlein. He refuses to talk at first but Carter points out that he's just one man. Heinlein finally tells them that Kohl was arrested 24 years ago in a joint American-German operation. He was recently transferred to a minimum-security facility and immediately escaped, and the Germans want him back in prison. Since he was jailed without trail, Kohl isn't supposed to exist and no one wants an international incident. Before Heinlein can say anything further, a lawyer from the German Consulate arrives with a writ from the State Department ordering the extradition of the prisoner.
Finch hacks the German society website and gets the membership list, and finds a man who fits Steiller's description. As Reese drives to the construction site where the man works, Finch calls Steiller and tells him that Kohl is on his way to kill him. Kohl emerges from the elevator and pockets the phone, keeping it on so Finch can hear the conversation. Steiller says that he saw how Kohl believed in the killing, and Kohl says that it was Steiller who trained him. He prepares to kill Steiller, who says that there's something he doesn't know.
As Reese arrives at the site and heads up the stairs, Steiller makes a call and says that he's the only one who knew. A woman at the other end answers: Anja. Steiller explains that she found him a few years after they defected, and that she was afraid of her husband. While Kohl is distracted, Steiller attacks him but Kohl throws him over the edge and the man falls to his death. Reese arrives too late to prevent Kohl from escaping. He's overheard the conversation and realizes that Kohl is going after Anja next because she betrayed him.
As Heinlein is deported and leaves the station, Fusco figures that at least Carter's mystery man gets results. Carter doesn't see it that way, and Fusco secretly sends the car's GPS tracking signal to Reese. Reese figures the route to the airport and sets up with a sniper rifle while Finch acts as spotter. When the car approaches, Reese shoots the engine and it goes off the road. Reese confronts Heinlein and demands to know where they can find Anja. Heinlein claims he can do nothing but secretly slips Reese the address. Reese and Finch then head to Anja's home in Morningside.
Kohl goes to Anja's apartment, takes out the security cam, and goes inside. Reese is already there and tells him that Anja is safe. He covers Kohl with his gun, but makes the mistake of getting close enough for Kohl to knock him out.
Finch takes Anja to the police station, but she says that she has to make a call first.
Kohl ties up Reese and demands to know where he can find Anja. When Reese refuses to talk, Kohl prepares his poisoned needles. Reese tells him that he withstood torture for 16 hours in Kandahar and didn't give up his name. Undeterred, Kohl inserts a needle into his ulnar nerve at the humerus.
Two American contacts arrive at the safehouse and Stanton offers them drinks. Reese then explains that they're looking for Alim Assir, a terrorist. The contacts say they sent their information to Langley, but Reese says that Assir escaped the country and they want to know how. They two men claim that Assir bribed customs, and Stanton jokingly asks how much he paid them. She then shoots both men dead.
Carter gets a call from the Germans about how Reese intercepted them. She goes to the scene to find out if Reese left a trail, while Fusco gets a call from Finch. Finch warns that Reese hasn't checked in and tells Fusco to do what he can get. Once Finch hangs up, he turns to Anja, who hasn't been able to contact the person she needs to, and says that she needs to trust him.
Reese still refuses to talk and Kohl admits that he was good at killing and has taken lives. The Stasi recruited him and Kohl left his country to kill whoever he was ordered to kill. Reese says that he was the same and warns that revenge won't help. Kohl insists that he has to see Anja and then applies a needle to the brachial plexus.
Anja tells Finch that Kohl loved her when he was with her. One day he came home and told her about the betrayal, and they traveled separately to the Soviet Union. The Americans found her and showed her photos of the people that her husband had killed. They staged the car accident and she started a new life in the U.S.
Kohl takes a break from torturing Reese and finds a photo of his daughter, Marie. Reese tells him not to do anything stupid, but Kohl searches through his wife's apartment and finds a photo album that Reese hid. As Kohl looks through it, Reese says that it's too late for the two of them, but Marie has a chance for a normal life. Kohl prepares to kill Reese rather than risk him coming after him, but Fusco arrives and orders him to surrender. The ex-Stasi agents opens fire and gets out, and Fusco unties Reese.
Marie is leaving class for the night and finally checks her phone. Before she can read her messages, Kohl approaches her with a gun and orders her to call Anja. Kohl arranges a meeting with Anja in a nearby park but insists that his ex-wife comes alone. He tells Marie that he knew her father and asks if Anja told Marie about him. Marie says that she was told her father was a soldier and died a hero, helping her get out after the Berlin Wall. Kohl says that he knew her father, once. Finch and Anja meet Kohl and Reese arrives behind Kohl.
Carter receives an anonymous call that the shooter is in the park and arrives with a squad of man. Fusco is already there, and they start searching the park.
Anja explains that she learned what her husband really was, and she was pregnant and trapped. When Marie asks who Kohl is, Anja admits that Kohl is her husband and asks for his forgiveness. Kohl says that he had to see both of their faces, and that a part of him has always been with her. He then raises his gun and Reese has no choice but to shoot him. He tells Finch to get Marie and Anja out of the park, but Kohl tells Anja that she was right to fear him. After they leave, Reese checks the clip of Kohl's gun and realizes that it was empty. He sits down next to Kohl, who says he wouldn't have hurt Anja. When Reese asks how he knew he'd shoot, Kohl says that Reese is a soldier just like him. He says that they took everything he had except for the part of him that survived as Marie, and then dies.
When Fusco and Carter arrive, they find Kohl's corpse. Reese watches from the bushes.
Stanton tells Reese to dispose of the gun and the dead contacts. When he points out that she killed them without confirming their guilt, Stanton says that a reliable anonymous source reported that they let a mass murderer escape. She insists that the threat is real and that Reese's country needs him. As Stanton leaves, she tells Reese that he's to ignore any old friends that he might because they're walking in the dark. She then decides to call him "Reese."
Sometime later, Reese and Finch visit Kohl's grave. They figure that the German authorities will sweep everything under the rug and pretend that Kohl never existed. The two men wonder if anyone will care for their names, and Reese figures that someone will only care after they're dead.