In Boston, Peter steals gas from a parked car at night and then goes to a local pawnshop. As the owner asks what he wants, an Observer comes in and, curious, starts reading Peter's mind. Peter blocks him by thinking of the Red Sox, but the Observer realizes something is wrong. Peter goes out and the Observer orders his loyalist men to detain Peter. He runs into the sewers and they toss an explosive down, and Peter runs away as it goes off.
When Peter wakes up the next day, he is out in the open. A boy is playing the harmonica and looks curiously at him. He explains that Peter came out of a nearby storm drain and points out that he's bleeding. The boy goes on his way, still playing the harmonica.
At the Harvard lab, Walter and Astrid continue digging through the amber and remove another video tape. Walter complains that it's taking too long and Astrid goes to clean off the tape. Peter returns and explains what happened. He admits that the Observer did get an image of Etta but points out that she is already a fugitive. Peter assures them that the Observer didn't pick anything else up but wonders how they can beat opponents who beat minds. Etta assures him that he did the right thing by blocking his thoughts and assures Peter that he can learn to do it effectively. She tells them that she plans to teach all of them. Meanwhile, Peter gives Etta a replacement necklace that he bought for the one she gave up so they could fix the laser. Etta hugs him and puts it on, and Peter smiles at Walter.
At the pawnshop, Captain Windmark is playing with one of the electronic toys when Phillip Broyles comes in on Windmark's orders. Windmark plays back a recording of the store tapes and asks what is the purpose of the necklace that Peter bought. He wonders why Peter would put himself at risk for something so unexceptional and thinks that the resistance has tipped them off to the Observer movements. The Observer points out that one of Broyles' men failed a security test and tells Broyles to get information about the resistance through him. When Broyles complains that they didn't tell him about the man, Windmark points out that he should have known but he didn't, and Broyles goes to look into it.
Walter and the others play the next partially-damaged tape, which has Walter talking about his mother would take him on tours into New York City and where he hid his most prized possession. The rest of the tape is ripped but Walter says that he knows that it's at Newark Penn Station. There are both Observer and loyalist guards and they figure that they're going to need an extensive diversion. Walter points out a cabinet inside the amber and says that they have to get to what is under it.
Once they dig through the amber, Walter reveals a hidden trapdoor. Below it is his collection of Fringe items that he collected over the years. Walter suggests that they create some Fringe cases of their own. The others are surprised that Walter was able to hide it from them all these years and he assures them that it was safer if he didn't give the items to the government. Walter considers the dimension portal but Peter says that there has to be a better way. Next, Walter finds an old doughnut hole covered in jelly and tries a bit. He assures the others that the jelly is still good.
Broyles watches as an Observer interrogates Broyles' security man, Holden. The Observer plays a video of Holden's previous interrogation and the seemingly innocuous questions that he asked him. He then informs Holden that he lied on the video and that he's a member of the resistance. The Observer begins telepathically digging deeper, pointing out that someone forged his paperwork to put him into position. Holden begins to twitch as he tries to block his thoughts but the Observer persists, asking where Peter Bishop and the others can be found. He realizes that Holden overheard Anil say something but then switches to something else that interested him: the dove. Holden begins to bleed from his eyes as the Observer demands to know who the Dove really is and where he can be found. The resistance member says that no one knows and the Observer looks at the camera, aware that Broyles is watching him
In his office, Broyles takes out a gun as the Observer comes out and says that Holden only had bits and pieces. He also explains that Holden heard Anil mention Peter Bishop in a lab in sector B, the old Harvard University. Broyles simply nods and the Observer says that he knows that Broyles had a relationship with the fugitives at one time. When Broyles wonders how he knows, the Observer says that Windmark told him and that the captain said he would tell Broyles. Broyles admits that he knew them but it was a long time ago, and the Observer says that the fugitives are in the lab. He studies Broyles intently and then says that he will make his report. Once he goes, Broyles sighs in relief and removes his hand for his holstered gun.
Walter and Peter play with a potato cannon while Astrid nervously removes a sample from another weapon. Meanwhile, Olivia and Etta review the security of the subway station and realize that the Observers have assigned more men. Olivia notices Etta playing with her necklace with a bullet on it and Etta explains that she found it at their old house at Quincy Street. Etta says that she took it so that she could have something to remember her mother and father. She figured that it was important and Olivia insists that she keep it. She does ask to see it and explains that Peter called it the bullet that saved the world. Before she can explain, Etta receives a text message that the lab has been compromised.
Broyles finishes sending a message and gets into the elevator with a different Observer. They ride down together.
Etta tells everyone that somebody she trusts gave her the information. Walter says that they can't leave everything behind or their plan will fail. Olivia says that they have to reamber the lab.
The loyalists break in a bit later as Broyles and Windmark watch via remote. The loyalists report that there is nothing in the lab. As they return to base, Astrid emerges from an air vent. Meanwhile, Windmark wonders how the reading from the prisoner was deceptive. He realizes that Etta somehow hid her thoughts from them and wonders if other humans can as well. He looks suspiciously at Broyles, who merely looks back at him.
Walter drives the car up to the subway station and asks for directions. An Observer arrives as the loyalist guard asks for his travel papers. The Observer tasers him briefly and then demands to see Walter's paper, and Walter dons a gas mask and sprays them with a chemical substance causing their faces to seal over with scar tissue. Peter, Olivia, and Etta get out of the back and they drive the car through. Walter and Peter go in the front while Olivia and Etta drive around the back. Inside, a guard gets a security warning.
Peter and Walter find the mark Walter left indicating the vent where he hid the plans. They open the vent and Peter takes out the tube with the plans. Outside, Olivia and Etta wait in the car. They finally don gas masks and go.
A guard and an Observer check on Peter and Walter, and Peter guns them down. Outside, Olivia and Etta fire gas grenades with the scar-growth gas while Peter and Walter get out and Peter fires. They drive off as the loyalists suffocate, unable to breathe. However, one of them attaches a tracking device as he clutches at the car in his death throes.
At his office Broyles packs his laptop and then takes out an old photo of Peter and Olivia and contemplates it.
The team pulls over and Walter removes the plans from the tube. It contains a formula beyond anything he's ever seen, in his handwriting, and Walter wonders if September dictated the equations to him. As they prepare to go back to the lab, Etta tells them that someone wants to see them. Broyles drives up, gets out of his car, and greets them, smiling. Olivia smiles back and hugs him, and Peter and Walter greet him as well. They realize that Etta didn't tell them about Broyles in case they were read. Broyles says that he had to see them and that five years ago he met Etta and realized she was their daughter. Once he told her who he was, he had her transferred to his section. Since then, Etta recruited him into the resistance and taught him how to block his mind over the course of a year.
Windmark examines the vent and the loyalists explain what they used. The captain realizes that they took something and a loyalist guard arrives to inform them that they've pinpointed the signal on the tracker.
Broyles supplies the others with weapons, including anti-matter batons that will destroy everything in a 100 meter radius. An Observer arrives and Broyles tells him that he apprehended them, and then shoots him. Olivia realizes that they attached a tracking device to the car and Broyles warns that they can't escape in car. Etta gives Broyles the plans and tells him to protect it at all costs. As he drives off, another Observer teleports in and stuns Peter with an air-gun. Etta kills him and runs off with the others, while Windmark and another Observer teleport in and trace their escape route.
The team ducks into a warehouse while the Observers and their loyalists close in, covering every exit. An Observer teleports in and Etta kills him, but loyalists open fire and the team is forced to take cover. Etta and Walter are cut off from Peter and Olivia, and Etta tells Walter to run and provides cover fire. As more loyalists arrive, Peter goes after Etta and Walter, and Walter gets separated from Etta. An Observer teleports in behind Etta and knocks her through a window, and Windmark arrives as she tries to get her gun.
Walter emerges from hiding as Peter and Olivia find him.
Windmark looks at the necklace and realizes that Peter bought it for her. He asks her why Peter bought it and scans her mind. Concentrating, he sees images of Etta as a young girl in the park with her parents. Windmark realizes that Peter bought it out of love. Etta grabs a knife from her boot and tries to stab him, but Windmark easily blocks him and points out that she never knows when to give up. He releases her and steps back.
Olivia and the others hear a gunshot.
Etta collapses to the floor and Windmark studies her for a moment before turning and walking away. The others arrive and insist that they have to move her. She tells them that they have to leave her and reveals that she's holding anti-matter baton. Olivia tells her daughter that she loves her and Etta says that she knows. They hold hands for a moment and Olivia takes the necklace. Peter refuses to leave his daughter but Walter, crying, says that they have to go.
Outside, the loyalists report that they're sweeping the building. Windmark realizes that the others would go back for Etta out of love. They go back to where she is lying on the floor and Windmark realizes that the necklace is gone. He sees the anti-matter baton... just as it explodes. Windmark teleports away but everyone else is killed in the blast.
Olivia, Peter, and Walter watch from a distance and Walter says that they need to leave. Olivia looks at the necklace as Walter tells Peter that Etta is gone and they have to go.