A doctor meets with a patient, Chet Williams, and assures him that his cancer is treatable at the early stages. Chet isn't convinced and the doctor assures him that they'll get through it.
Later, Chet waits at a bus stop when an Asian man, Neil Chung, sits next to him. He says that tissue connectivity goes last. When Chet wonders what he means, Neil says that the treatment won't work and Chet will eventually die because they didn't catch the cancer in time. He describes exactly how Chet will die from a single tiny mole. When the bus arrives, Chet is dead on the bench.
Agent Farnsworth travels across the bridge to This Side.
On the Other Side, Colonel Broyles calls in Bolivia and Lee to inform them that Farnsworth has crossed over to This Side on her own authority. Bolivia figures that after the day that Farnsworth has had, she knows why she went to This Side and goes to get her on her own.
At the lab, Peter is still working on the Machine plans with Walter. Walter wants to get eggs and says that he prefers Lincoln. Lincoln is attending his goddaughter's birthday party. Farnsworth comes in and Walter initially mistakes her for Astrid but soon realizes who she is. Astrid arrives with Olivia and is startled to see her counterpart. Farnsworth explains that she came to meet Astrid for the first time, and that she didn't know what to do. She talks about a man's funeral and then asks Astrid if she loved her father. Astrid realizes that Farnsworth's father is dead on the Other Side.
Before they can pursue the matter, Olivia gets a call. Walter offers Farnsworth food, and Olivia tells them that Bolivia is on her way to sort things out. Olivia wonders if she should stay with Farnsworth, but Walter says that he'll watch over her.
Olivia, Peter, and Astrid meet Broyles at the bus stop. Chet has bled from the eyes and Walter tells Astrid to confirm that his organs didn't liquefy. He does suggest that there's a legend of the Tears of Ra, a potion used to euthanize pets in ancient Egypt. Walter tells them to bring the corpse back to the body, and Farnsworth is surprised that Walter talks through Astrid. He admits that it's a pleasant experience. Meanwhile, the Fringe team leaves, unaware that an Observer is watching them from within a nearby window pane. He calls to tell his people that they have located it.
Back at the lab, Astrid and Farnsworth run an autopsy on the body. Walter confirms that an unusual chemical compound was the cause of Chet's death, but that the compounds couldn't have interacted. He admits that it's unusual science and was killed by a poison that no one has invented. Bolivia arrives and Farnsworth suddenly suggests that the poison isn't predictable, and someone had to assume that the toxins would intermingle even though they can't. Someone would have had to see the future in order to create the chemical. Walter agrees, saying someone with godlike powers would have had to create the poison. He leads her off to pursue the matter, while Bolivia settles in to stay for the immediate future.
A well-dressed woman, Kerry Watson, buys alcohol at a bodega and then throws it in the garbage. Neil comes up behind her and tells her that she won't win, she'll take a drink, and it's downhill from there. He tells her that her drinking will destroy the lives of everyone she loves. When Kerry insists that he can't see the future, Neil says that everything happens right now and sprays a substance into her face.
At the lab, Walter gives Bolivia all of the items that she left behind when she ended her mission, including a small metal box which he assumes is a spy gadget. She realizes that she got to him and suggests that he enjoyed having her around. Astrid, Olivia, and Peter call in from the scene. The EMT tells them that the dead woman bled from her eyes. Walter starts to ask Astrid to gather a DNA sample, but Peter takes a DNA sample and confirms that she inhaled something. As Walter starts to tell Astrid to bring the body back, Peter says the same thing first.
Back at Harvard, Walter asks Peter to sharpen some scalpels rather than let him do the autopsy. Peter reluctantly does so and Farnsworth notes that Walter is angry with his son. Walter insists that Peter isn't his son but Farnsworth pursues the matter, asking if he loves Peter. After a moment, Walter admits that Peter is a reminder of the son he had. Farnsworth suggests that it would be preferable if he chose to believe Peter really was his son, and Walter doesn't have an answer for her.
Olivia and Bolivia go over the records. They discuss Peter and Bolivia admits that she prefers nice guys rather than sneaky guys like Peter. They're unable to find a connection between the two victims, but Olivia insists that there must be one.
At Logan International, Neil is posing as a TSA inspector. A particular man arrives and Neil wishes him a nice flight. He then writes the name Jared Colin down and waves him through.
Later in Back Bay, Boston, Jared is going to his car while talking to a partner, Bill. The Asian man approaches him, takes out a blue rod and reads from it, and informs Jared that the next call he makes will kill him. He'll be on the phone when he's driving and will flip his car, leaving him a paraplegic. The man who runs the group home where Jared will end up will let him die, and Jared will die painfully. When he tries to spray Jared, the man runs off but is hit by a car.
Fringe Division gets word of the incident and goes to the hospital. Jared says he's never seen the man before. They talk to Doctor Brady, who tells them that Jared will never walk again. Jared says that he was selling his company to his scumbag partner, and he was planning to start over. However, he was delayed by the TSA at the airport and missed his flight. Jared doesn't recognize the other two victims, and explains that Neil said he wanted to put him out of his misery and acted like he was some kind of saint. The man admits that he wishes that his attacker had killed him.
At the lab, Astrid and Farnsworth go over the files. Astrid offers to make some coffee and Farnsworth explains that coffee is rare on the Other Side. Meanwhile, Bolivia continues to hang around Walter and realizes that he's still angry at her. Walter explains that he's considering the case and figures that they're looking for a compassionate killer who believes that he's saving his victims from further suffering. Meanwhile, Farnsworth realizes that all three victims went through Logan International, even though it was months apart. Further, the agent confirms that they were each screened by the same security agent, TSA Badge 0047.
Peter and Olivia got to Logan International and approach the TSA agent, who has the blue rod at hand. When he spots them, he hastily takes off. They try to follow but the security guard stops them per Federal regulations and their target gets away.
Olivia and Peter go to the Massachusetts Institute of Technology and learn that Neil was an advanced mathematics professor. Neil's coworker tells them that Neil lost his mind. He thought that math was the key to solving the mysteries of the universe, and came back from summer break at his lake house. At the time he said that he had found something, and then became intrigued by high-level differential equations. Neil believed that if he could solve the equations, he could flatten time and space, seeing the past, present, and future simultaneously. The math professor became obsessed with solving the equations, left the college, and went back to the lake house... at Reiden Lake. As they leave, Olivia asks Peter what is going on, since he appeared at Reiden Lake. Peter notes that the Observer can also see all times simultaneously, and it was an Observer that saved him as a child. Olivia wonders if an Observer is using Neil, and Peter suggests they drive to Reiden Lake.
At the lab, Farnsworth watches Walter meditate and realizes that Astrid cares for him like a father. The agent then admits that she couldn't give her father what he needed because of the way that she is, and that he wished Farnsworth could love him in a way he could understand. She asks Astrid if her father would have loved her if she was normal and then walks away.
Peter and Olivia arrive at Reiden Lake and discover that the door to Neil's lake house is unlocked. They go inside and find the wall covered with equations. Peter finds newspaper articles about how Neil's twin brother and father were killed in a car accident when the professor was a child. There are also photos of various saviors taped to the walls, and a photo of Neil with his mother, Anne.
At his mother's home, Neil looks the blue rod in a safe and then removes a gun. He loads it and walks past his mother. She asks him what he's doing and why he's there to say goodbye. Neil tells her that he left MIT, he wasn't fired, and then turns and stares at her. After a moment he tells his mother that he heard her the night that his brother Alex died. She said that she thought God had taken the wrong son, and Neil admits that he thought she was right and he would never be that good. Now he has a way to see the future. When Anne talks, Neil echoes everything she says, having seen it happen. He insists that God gave him a way to see the future so that he could give people mercy. His mother apologizes, saying he should never had heard what she said that night. Neil figures that God took notice because of her, and says that like Jesus, he knows that people are coming for him. He says that he understands God's plan for him and draws the gun.
Olivia and Peter break in but Neil ignores them. He tells Anne that the preacher at the funeral said that angels don't belong on Earth, says he'll see her in Heaven, and then turns on Olivia with the gun in his hand. He fires a shot over her shoulder and Olivia has no choice but to shoot him dead. Later, the EMTs take the body and Olivia realizes that Neil didn't intend to hit her. He couldn't kill himself because he wouldn't go to Heaven, and that he believed he was helping people. As they go, Olivia admits that Peter makes a good partner.
That night at the lab, Farnsworth and Bolivia prepare to leave. Walter gives her a hug and Farnsworth reluctantly accepts. Bolivia shows him the object that she left behind and reveals that it's a mint holder. Walter smiles and offers her a piece of licorice, and admits that she might have positive qualities. Meanwhile, Astrid tells Farnsworth that she isn't close to her father, and that he's a very complex man who doesn't show emotion. However, she knows that he loves her. Astrid tells Farnsworth that she shouldn't regret being more for her father, because it wasn't her. Farnsworth thanks Astrid and they shake hands.
Astrid goes home that night and herfather greets her. He's a very emotional man and hugs her when he knows that something is wrong. Astrid tells him that she loves her and he assures her that he loves her as well.
Anne is at home, asleep in her chair. Two Observers come in and remove the blue rod from the safe. They realize that it belongs to September and he lost it in 1985 when he didn't save the boy. As they go, one Observer tells the other that September didn't obey his instructions and Peter Bishop has returned.