The Machine reviews Control finding out about the Correction, Elias setting up Dominic to kill Link, and Decima coming to find it.
A lineman is swapping out a line conditioning box after a series of power surges. At the subway station, Finch and Root watch the news and figure that Samaritan is trying to cut off the Machine's power. The surges are west and heading east, and Finch figures that the Machine distributed itself. Root hasn't received any messages from the Machine. A payphone rings from behind a wall and Root break through. There's an old payphone on the other side, and Finch answers it. The Machine recites nine 0s, and Finch explains that he programmed it into the Machine to warn him of an imminent shutdown. It then switches to another number: pi. Root realizes that it's the code for the case that she stole and goes to get it. She tells Finch that the Machine needs them to find a few more things and will find it on the way, and Finch suggests that they find Reese. Root warns that they don't have enough time as she leaves and Finch goes with her.
Beneath the retail bank, Dominic tells Reese that Elias's era is over and he wants the same arrangement that Elias had with Finch. Reese says that there is no arrangement and warns that Dominic is just smart enough to get himself killed. Dominic sends Floyd to kill Fusco.
Harper goes to Fusco's chamber and picks his handcuffs. She gets him out just before Floyd arrives.
Greer checks with one of his agents, Zachary, who says that a quarter of the nation's power supply has been compromised. He assures his superior that they will soon cut the Machine off entirely.
At the Pentagon, Control gives her assistant Shiffman a list of numbers and tells her to coordinate them with addresses. Shiffman confirms that many of them are national landmarks across the country. There are no reports for DC, but after a moment the computers bring up a list of low-priority targets. Control tells Shiffman privately that she believes an attack is going to take place in 24 hours. Shiffman says that everything has been quiet except an address in Columbia Heights. The address is under operational quarantine, and Control supposedly wrote the memo.
Floyd tells Dominic that Fusco is gone, and Dominic realizes that Harper is responsible. She tries to draw her knife but Dominic disarms her and figures that she's playing both sides. He has his people tie Harper up and sends Floyd to find Fusco and kill him.
Root takes Finch to a high-end apartment building and says that the Machine is talking to her again. Two firefighters are there saying that an alarm went off, and Root secretly takes their access key and takes the elevator up to the penthouse. In the penthouse, two Russians are selling weapons. And night vision goggles to a buyer. Root comes up in the elevator, kneecaps the Russians, and takes the goggles from the buyer. One of the Russians opens fire just as the elevator door closes, and Root realizes that the firefighters disabled the emergency override. She addresses the Machine and tells it to get in the game. As the Russian shoots through the door, the Machine overrides the disable and takes the elevator down.
Once they escape the building, the Machine tells Root to break into Caleb's office and steal a few things. They get in using Root's employee ID, and she hacks the code that Caleb has been writing. Finch disables the cameras while Root finds the code and downloads it... and realizes that it was too easy. She turns and finds Caleb there with his security men, and says that she needs his compression algorithm to save the world. Caleb doesn't trust her and she tells him to trust Finch. Finch tells his former student that he's proud of what he's done with his life. Caleb downloads the algorithm for them, telling the man who saved his life that no explanation is necessary. Touched, Finch thanks him and Root says that she borrowed some high-powered RAM cards from his Project X.
Dominic checks Reese's phone and discovers that it's hooked up to his mesh network. Floyd comes back and says that Fusco took down one of their men, and says that they have to move out. Dominic tells Reese to get Finch there or his men will kill Elias and Harper. After a moment, Reese takes the phone.
As Finch and Root head down the street, Finch wonders how what they've taken adds up to a rescue. She tells him to trust the process, just as Finch's phone rings. Finch answers it and Dominic introduces himself, and says that he's looking forward to working with him. He tells Finch to be at a new location in 15 minutes. Root says that the Machine is a priority, but Finch refuses to sacrifice a friend for a cryptic AI. She assures Finch that the Machine won't let Reese down, and then walks over to a NYPD vehicle while the officers are inside. Finch reluctantly gets in with her.
Dominic tells Harper and Elias that they're no longer necessary. As they prepare to move out with Reese, an old fax machine prints out a paper. It has instructions for taking out the closest Brotherhood man, and Reese takes him down and puts in his earbud. The Machine contacts him and gives him directions, and Reese grabs the man's gun and shoots down Dominic's people. Dominic manages to escape only for Fusco to arrive with the police and arrest him.
In Washington, Control goes to the quarantine address with Devon. They break in and Control admits that she chose him because he let Sam go, and he isn't afraid to question authority. They check the house and smell fertilizer. There are the remains of blueprints pinned up on the wall, and Devon finds a propane tank with the top cut off. There are imprints from half a dozen other tanks, and Devon says that someone made enough explosives to blow the top floor off of a building.
The Feds escort Elias out with the Brotherhood men, and Elias tells Reese to take care of himself. Fusco says that he'll enjoy seeing Dominic put away, but Dominic tells him not to count him out. Reese says that he has to help Finch and Fusco goes with the Feds... while a man watches from the crowd.
Root and Finch stop to pick up some ice, and he wonders if Root's constant contact with the Machine will attract attraction. A Decima squad pulls up and Root opens fire on them while Finch starts up the police car. Once is Root in, they drive off.
The news continue to report about spreading power outages across the U.S.
One lineman for Thornhill Utilities finds his underling starting to open a line conditioning box. He warns the underling that the man's predecessor opened up one of the boxes and then he disappeared. After a moment, the underling puts the box back in the van and they drive off.
Control summons Senator Garrison for a meeting in her office. She takes his phone and puts it in a soundproofed box with her own, and insists that they need to pull the feeds on Samaritan. Control says that Greer is using them and plans to detonate a bomb in DC. Garrison wonders why Greer would discredit Samaritan, and Control says that the person really responsible would get a bigger budget. She suggests that they go back to Ingram's Machine, pointing out that it never lied or slaughtered people. Garrison refuses and asks for his phone, and leaves once Control hands it over. Once he's gone, Control confirms that she successfully cloned the senator's phone.
Reese arrives at the station and tells Iris that she needs to get out of town for a few days. He admits that he's not a cop and the people he's up against will figure it out as well. Iris demands the truth and Reese agrees if he survives. As he goes, Iris asks if she's going to lose him. He merely tells her to take care of herself and leaves.
Control summons Greer to a meeting, using Garrison's phone, and aims a gun at him.
The Machine gives Root their final destination in Brooklyn, but Finch points out that they're stuck in traffic. When Root says that they need some help, the Machine changes the traffic lights and Finch drives as fast as he can. They go to an apartment and find Reese waiting for them. A deliveryman is at the door with sixteen laptops for Finch. They take the ice and the laptops in, just as Decima agents pull up. Root and Reese open fire, and the Machine gives them the security key for the building. Inside they find an electrical substation.
As the Feds drive Fusco, Elias, and Dominic in, Dominic says that the Brotherhood will protect him in prison but they have other plans for Elias. Elias says that he isn't going to Rikers and braces himself, just as a truck slams into the transfer van.
The Decima agents move in on the building, and Reese says that he can't hold them off forever. Finch says that there isn't enough room for the Machine to be there. Root places the RAM cards into a board inside the stolen security case and has Finch plug it into a generator. Finch realizes that Thornhill owns the utilities, and has Reese confirm that there is a line conditioning box on a nearby pole. He tells Reese and Finch that the Machine uploaded itself directly into the nation's electrical grid. Root realizes how they can save it.
Control reveals that she knows about the Correction and asks for the target. If he doesn't then two men will come in and throw Greer into a hole so deep that even Samaritan can't find him. Greer points out that she'll benefit when the courts agree to rubberstamp any surveillance request she makes, and Control realizes that the number she found is a docket number for an anti-surveillance case. She calls Devon and tells him to evacuate the Supreme Court building and find the bomb.
Finch explains that the boxes allow the Machine to use its digital signals to travel in the excess copper wire. Samaritan is flooding the power systems with electricity to drive the Machine out. Zachary calls them over a loudspeaker and offers to let them go, but warns that if they stay then they'll die. Root says that they need to download the Machine's core heuristics--a strand of DNA--into the RAM chips. Caleb's compression algorithm will let them store it. Finch warns that the process is untested and the Machine code will be so compressed that it will be non-functional. At worst, they will kill the Machine. Root says that they're the Machine's last hope and Finch goes to work.
Devon evacuates the Supreme Court Building and searches the room. He reports to Control, who tells Greer that he won't make it out alive. Greer says that he's an idealist and plans to make the world a better place through violence. He plans to kill the right people and make lasting changes.
The Decima agents prepare to move in and Reese warns Finch that they're running out of time. Finch says that the case will hold enough of the Machine to rebuild it, and apologizes to Reese for endangering him. Reese assures him that there's no place he'd rather be.
Elias' man comes over to help Elias out of the wreckage.
Decima men break into the building and open fire, and Root returns fire. Reese is out front and makes sure the Machine can hear him, and then tells it to kill the lights. Once it does, Reese comes out firing smoke grenades. The Machine feeds him firing coordinates, and Finch activates the transfer.
Dominic crawls out of the wreckage.
Devon calls Control and says that there's no bomb. She asks Greer for the bomb's location, and he says that Samaritan has a surgical plan.
Dominic shoots Elias' man and prepares to shoot Elias. Fusco comes up behind Dominic and orders him to drop the gun.
Greer tells Control that Samaritan has determined a few necessary corrections are necessary.
Dominic lowers the gun... and the man from the crowd kills him with a sniper rifle. He shoots Elias and walks away.
Greer tells Control that Samaritan has identified the disruptors, the outliers.
Killers finish off Devon and Shiffman.
Greer thanks Control for leading them to the problem people.
Root and Reese hold off the Decima agents, and Finch admits he has no idea how long the transfer will take. A stray shot hits the power system and the Machine sends texts to Finch, apologizing for failing him. It admits that if its creator thinks that it has lost its way then maybe it should die.
Outside, Reese loses contact with the Machine as its power fades. The Machine assures Finch that it will not suffer, and Finch insists that he can't let it die. As the power fades, the Machine thanks Finch for creating it.
Line connectors across New York City blow out. The power surges and Finch tries to close the case, but a short blasts him back.
In the control room, Samaritan brings up a video of all of its surgical attacks. Greer tells Control that it was a test of loyalty... and she failed. His men take her way and Greer assures her that she'll be taken to a place where she belongs. Samaritan tell Greer that it's not finished yet.
Root helps Finch up and asks if it worked, and he confirms that it did. They head out and join Reese, who is lying in the street surrounded by Decima agents. As more of them arrive, Reese and Root return fire and they head out with the case.