Night and Olivia sits in a car in the rain. Loyalist workers are taking down the Etta resistance programs that have cropped up all over the city. Finally Anil runs to the car and hastily gets in. He shows her the piece of Observer tech that they insert into their own brains, the same one that Peter used, and assures Olivia he had no idea what Peter intended to do.
At Etta's apartment, Peter is charting Windmark's future on a clear board.
Windmark and his lieutenant enter an apartment building and teleport into the apartment. They find the clear board covered with Windmark's timeline and the lieutenant warns that Peter has the ability to track futures. The board shows Windmark in the apartment at that precise moment. On the street below, Peter watches in satisfaction.
At Harvard, Walter and Astrid watch another of his tapes directing them to get an electromagnet from a junkyard in Fitchburg. Meanwhile, Olivia makes her way in and tells them what Peter has done to himself. She asks Walter to find out if they can neutralize the tech and he promises to start running diagnostics. He points out that it's meant to be integrated with organics and he has to have it interact with a human brain. Walter prepares to use the porcupine man brain's specimen and sends Astrid to get it.
Peter calls and Walter tells him that he has to come back to the lab. His son refuses and warns them that Etta's apartment is compromised. Peter says that he's in control and Walter reminds him of his promise to keep him from slipping. Walter begs him to come back but Peter repeats his warning and hangs up. Olivia says that she can't stay there and goes to find the magnet alone, keeping her promise to Etta to carry out the plan.
In New York, Peter sees Windmark's future where he walks down the street with his lieutenant. He takes a cup of coffee that he saw fall over and places it in the proper position that he foresaw. Windmark and his lieutenant walk past just as a man knocks the cup over, spilling it on Windmark's shoes. The man hastily tries to clean them off, delaying Windmark so that he comes to a red light on at the street corner. Satisfied, Peter leaves.
Olivia arrives in Fitchburg and drives to the junkyard. Children are playing among the ruins and one little girl follows the car on foot. Olivia approaches two men gathering junk and offers to barter with one of them, Carlos. When he learns that she wants a magnet, Carlos seems startles and tells her to wait there while he goes to find someone. As Carlos leaves, Olivia notices a security camera mounted on a poll.
Carlos goes into a garage where a woman, Simone, is negotiating over the phone. He tells her that there's a woman wanting a magnet and shows Simone a hologram, and Simone says that it's her. She tells Carlos to send them now and watches the hologram with shock and interest. She then goes out and approaches Olivia. Smiling, she says that they've been expecting someone to come for the magnet and have it ready for her.
Simone takes Olivia to a truck with the magnet aboard, and explains that 21 years ago a man came there and talked to her mother. The man said that he needed a magnet to save the world, and Simone's mother assured him that she'd keep it packed up for him until he came back. Simone's mother had her promise to keep it until someone came for it. Simone and her mother never lost hope and now Olivia has arrived. She tells Olivia that there is diesel fuel on the way and knows that Olivia would rather wait until after nightfall to drive away. When Olivia asks how she knew that, Simone explains that she gets flashes around people and knows about the bullet in Olivia's pocket.
Walter examines the brain and prepares to insert the Observer tech as Astrid watches on the monitor. When Walter holds the tech piece up, it jumps out of his hand and into the brain, and they watch as it spreads through the cerebral cortex. It stops once it determines that the brain isn't suitable, and Astrid continues running a simulation on what it would have done to the human brain. It generates more convolutions, overriding the area of the brain that controls emotions.
While Simone waits for her men to return with the gas, the little girl approaches Olivia and says her name is Darby. Darby says that everyone is talking about Olivia and how she's on the reward wire. Carlos calls the girl away while Simone offers Olivia a glass of water. Olivia wonders if it's drugged and figures that it's a trap. She draws her gun and Simone drinks the water to demonstrate that it's harmless. The woman realizes that Olivia has no faith, but Olivia isn't interested and demands to leave. Simone says that she'll have the fuel when it comes, but she's welcome to leave in her car and come back with more people. As Olivia lowers her gun, Simone realizes that Olivia has lost her daughter twice. Before Olivia can respond, the men call to say the fuel is there.
Peter goes to a building under construction to continue his surveillance of Windmark. As he predicts Windmark arriving behind him, Windmark arrives behind him and says that Peter isn't the only one who can run futures. The Observer says that he's been making adjustments to Peter's future just like Peter has been adjusting his, and that he knows that Peter sent the briefcase that killed the other Observers. Peter teleports, attacking Windmark, and the Observer fights back. Windmark gets behind Peter, slams him into a wall, and says that was the last thing Etta saw. He warns Peter that emotions make him weak and prepares to stab Peter, feeding Peter Etta's last thoughts before she died. Peter shoves Windmark away as the Observer's lieutenant teleports in. Peter manages to stab him and teleports away, and Windmark teleports down to the street to try and find Peter, who has made good his escape.
As Simone takes Olivia to the truck, she insists that there are mysteries to the universe. She tells Olivia that her heart will find an intuitive way to deal with her loss, and says that Etta is still with her. Olivia dismisses Simone's gift as an anomaly and says that she knows because she's also an anomaly. She explains how she's seen and done so many things, but in the end people assign meaning to things that don't have any and it's all just numbers. As Olivia prepares to drive away, Simone smiles and says that she believes and that Olivia can't know everything.
At the lab, Walter has Astrid heat the tech with a hair dryer. She stops when Peter comes in and asks Walter to suture his shoulder, which is bleeding from the Observer's attack. Walter goes to work and Peter assures him that there is no pain. As he sutures the wound, Walter tells his son what he's discovered about the Observer tech and how it reshapes the parts of the brain relating to emotion. Peter already knows and tells Walter that it's incredible to experience the untapped potential of the human brain. Walter warns that the changes will soon be permanent, but Peter says that he needs to redirect Windmark through a square at 7:19 p.m. When he does, Peter will know that he's on the right path. Walter says that he won't allow it, but Peter says that when Windmark passes through the square, Etta will be avenged. Walter insists that his plan on the tapes is the one to follow and he needs Peter. Peter checks the time and says that he has to go.
As Olivia drives the truck back, she calls Anil and says that he'll have someone meet her and take her to a warehouse where she can store the magnet. She sees two wrecked cars up ahead and tells Anil that she'll call him back. When she gets out to investigate, Olivia discovers that one of the "victims" is a mannequin. The other man, Briggs, gets up and trains a gun on Olivia, while his partner Stanton steps out of the woods. The outlaws confirm that she's wanted and quickly subdue her.
The outlaws take Olivia and the truck to their hideout in an old building. Briggs assures his partner that he has everything covered and makes a call to the reward wire. He asks for a meeting at a truth church where they can't scan him and demands the reward money upfront. The operator takes Olivia's name and puts Briggs on hold. Meanwhile, Olivia wakes up in the next room and cuts her bonds on an old saw.
A loyalist informs Windmark that Olivia has been captured. The Observer okays the reward payment.
The operator tells Briggs to be at the truth church in an hour. Meanwhile, Olivia finishes cutting herself loose and confirms that there's still some pressurized air in a tank.
As 7:19 approaches, Peter breaks into the Observer building and sabotages the elevator wiring.
Windmark prepares to take the elevator down from his office but discovers that it isn't working. He goes down the stairs instead. In the basement, Peter seals the panel back up and leaves.
Olivia creates a fire using paint thinner and a rag. She then puts Etta's bullet in the air hose and waits. When Briggs sees the smoke, he comes to investigate and Olivia "fires" the bullet, shooting him in the head. Stanton returns and sees the smoke, and Olivia gets the drop on him. When he asks where Briggs is, Olivia shoots him and then pulls Etta's bullet out of the wall behind Briggs. She then calls Walter and tells him that she's on the way back to Boston with the magnet. He tells her that Peter was there a couple of hours ago and failed to convince him to remove the tech. Olivia looks at Etta's bullet and asks where Peter is.
That night, Peter watches from a rooftop overlooking the square. As he waits for Windmark, Olivia comes up and Peter points out the steps where Windmark will pass a fountain. When he does that, Peter will know that the Observer is back on the trajectory that leads to his death. At exactly 5:12 the next afternoon, he will meet Windmark face-to-face, surprise him and snap his neck one minute later. Olivia says that she won't lose Peter again and says that she's there because of her feelings. She warns Peter that he soon won't feel anything for Olivia or Etta. Peter looks at her and then explains that Windmark showed him Etta's last thoughts of her parents on the day that the Observers invaded. He promises to kill Windmark, admitting that he can't do it if he removes the tech.
Olivia asks what happens if the tech becomes permanent by then, and tells her husband that Etta is still with them. They have to hold onto their feeling for Etta rather than let her die for good. Peter checks the time as Windmark approaches the square, and Olivia asks Peter to hold onto Etta's memory. She promises not to lose him again and Peter remembers the day in the park. He turns to look at Olivia, who says that she loves him. More memories of his life flash through Peter's mind and he draws a knife... and cuts out the tech from his own brain. Olivia puts Etta's bullet necklace in his bloody hand and he collapses into her arms as she whispers that she loves him.