In Boston, an observer (but not The Observer, mind you) is watching people in the park. He zeroes in on one girl and approaches her, grabbing her roughly on the arm and telling her to come with him. She protests, drawing attention from a man who tries to come to her aid. The observer shoots the man and breaks into a car, which he manages to start with the touch of his finger. A park ranger fires on the observer, but misses and he drives off with the girl.
Agent Olivia Dunham is called in on the kidnapping. She connects with Walter and Peter Bishop, as eyewitness accounts lead her to believe that it is The Observer behind the abduction. Walter reveals that when he and Peter were drowning in a frozen lake 24 years ago, it was The Observer who dove in and saved them. Astrid provides them with footage from the kidnapping and Olivia realizes that the person behind the abduction is not The Observer. Dunham meets with Agent Philip Broyles and states that she cannot decide why an observer would kidnap someone. Everything she knows about The Observer makes it seem like he just watches and does not get involved.
At the Harvard lab, Astrid, Peter and Walter are pouring over a journal left behind by the kidnapper. A spot of blood on the pages leads Walter to assume that the kidnapper may be a hemophiliac. Astrid, however, is having no luck deciphering the language the journal is written in, though Walter secretly seems to recognize it. Astrid discovers that someone else has been investigating the symbols - Massive Dynamic.
At Massive Dynamic, Agent Dunham and Peter meet with SCIENTIST who is trying to determine the origin of the journal language. He shows them other discoveries that he has made - pictures of observers appearing at various moments throughout history, including the Boston Massacre, the execution of Marie Antoinette, and the assassination of Archduke Ferdinand. The SCIENTIST says that he thinks the observers show up at important, historic moments in human history. He says that he has seen an influx in appearances over the past three months, and wonders what's about to happen.
The Observer (the real one!) is shown sitting at a restaurant with another, older observer. The two men are downing hot sauce and spices when a third observer shows up, telling them that they have a situation with "Artist" - the kidnapper. The woman he kidnapped was apparently supposed to be on a specific flight, one which has already taken off. The elder observer says that he has created an "irregularity" and orders The Observer to contact "Donald" to fix it. Donald receives the message, a picture of Christine, the kidnapped girl, and loads a silenced pistol, preparing an assassination of his own.
At Christine's apartment, Peter and Agent Dunham learn that when Christine was a child, her parents were killed in the great San Francisco earthquake of 1989. The pair see an observer standing behind the family in the last photo taken of them. As Dunham and Peter listen on the radio, and as Christine and Artist watch from their hotel room, the news breaks that the flight Christine was supposed to be on has crashed. Artist explains that he saved Christine, but that she is not safe yet. He leaves her at the hotel and returns to the restaurant to confront the other three observers. He tells them that he has observed Christine for much of her life and that she is unique. He has seen Christine's future and that she must be important. The others determine that he must be mistaken; she was meant to die on that flight.
Walter has broken the code in Artist's journal. Unbeknownst to Agent Dunham and Peter, he sneaks off to meet Artist at a coffee shop. Artist says that he left the code as a means to get Walter's attention. Walter implores him not to take Peter, and tells him that he had a deal with The Observer. Walter says that he knows what he did was wrong -- but is then cut off by Artist, who tells him that he is not here for Peter, but that he needs Walter's help. He explains that he has upset the natural order of things, and that the others will not stop until Christine is dead. He wants Walter's help, as Walter has successfully upset the natural order of things in the past with Peter. Walter tells Artist that if the others cannot see why Christine is important, he must do something to make her important.
Peter and Olivia find Artist's apartment and go to investigate, thinking that Christine may be being held there. However, Donald arrives before them to find the apartment empty. He pulls a list of motels from the phone book but Peter and Olivia arrive before he can escape. He tries to shoot Peter, but Peter gets free and Donald bolts. Dunham and Peter search the apartment and find newspapers dating back to the 1800s. They are told that Artist has been spotted at a motel in Lowell, but Donald is also on his way there. At the motel, Donald is shot by Artist. Artist waits for Dunham and Peter to arrive and then allows himself to be shot by Donald, whispering "goodbye" beforehand. Donald and Dunham engage in a gunfight while Peter tends to Artist, who gives him his gun. Peter stuns Donald with Artist's gun and Dunham finishes him off. Peter discovers that Artist's body has disappeared; Dunham finds Christine hidden in the motel room.
The Observer drives away from the motel with a wounded Artist in the backseat. Artist tells The Observer that he saw Christine as a young girl, right after her parents had been killed, and that she was brave. He notes that she "crossed his mind" and reveals that he loves her. He asks if she will be safe, to which The Observer responds that she will. He says that Artist made her important, as she is responsible for the death of one of them. With this, Artist succumbs to his injuries and dies.
As the episode ends, Olivia finally gets to take her niece, Ella, to the amusement park as she had planned to do earlier. The two ride a rollercoaster together, as happy as Dunham has ever been. The Observer stands off to the side, watching them. The elder observer approaches him and notes how happy Dunham is. As the show ends, he notes that it's a shame that things are about to get so hard for her.