The team examines the Observer boy, Michael, for any sign of tech. When they don't find anything, Olivia asks Michael to communicate with them like he did in the other timeline. Walter and Peter also appeal to him but the boy doesn't answer, and Walter suggests that they try to enter Michael's mind like they did with September. They refuse and Walter grows increasingly agitated until he finally gives up. Once they're alone, Olivia wonders to Peter why Michael can't respond to them when he did before.
Olivia calls Nina at the Ministry of Science on her private line. As Nina's loyalist assistant listens outside, Nina tells Olivia that it's not safe and she'll call back in ten minutes.
A few minutes later, Windmark and his men arrive, walk past the assistant, and enter Nina's office. There's no sign of Nina and Windmark interrogates the assistant. All she can say is that Nina go a call on her private comm 20 minutes ago and took an early lunch. Windmark tells the assistant that someone in the office used a sublimation device recently. They hook up a machine to record the lingering sonic vibrations from the glass and hear Nina mention a child Observer.
Nina takes a van to a busy street and meets Olivia. She assures Olivia that she's glad to help and Walter and Peter bring Michael over. The boy doesn't respond to her and Walter complains that he's cold. Nina says that she there is a Massive Dynamic black lab nearby with tech they can use to communicate with Michael. As they go, Nina asks about Walter and Peter admits that his father is vacillating. She admits that she's agreed to remove the pieces of brain that are transforming him to his old self, and warns Peter that Walter may regress to the point where he no longer wants her to remove them. As Peter catches up to Olivia, he sees her looking at one of the resistance photos with Etta's face on them.
At the Ministry of Science, Windmark and his men wait for Nina to return. When she doesn't return, Windmark goes to the facility where the sublimation device was stored.
Nina takes the others to the black lab and Michael hesitates. Olivia stays with him while Nina and the others power up the main room. A dead Observer is stored in one cylinder and Nina admits that the resistance used the lab to study the invaders in an attempt to learn their method of communication. She suggests that the same equipment can be used to communicate with Michael. Peter goes back to Olivia and she admits that she still thinks of Etta every time that she sees one of the posters.
Nina lectures the group on how the Observer brains work while and shows them an electro-cognitive translator, an ecog. The device translates Observer thoughts into images that they can understand. Walter brusquely tells them to prep the subject and Peter reminds him that the boy's name is Michael.
Windmark goes to the storage facility while a loyalist officer informs him that they've been unable to locate Nina's comm device. The Observer speaks to one of the scientists, Roe, and informs him that they know that Nina is working for the resistance. Roe says that he has no idea where she is and the Observer telepathically confirms that he's telling the truth.
Peter puts the ecog on Michael's head while Olivia assures him that it won't hurt. Once they're ready, Olivia tells Michael to squeeze her hand if he wants to stop. She then asks him why he is so important to the plan, and Nina warns them that Michael's brain works differently than the Observers that they studied. She suggests that Michael has lost his empathic connection to Olivia and can't understand what they want, and proposes that the let Michael into one of their minds. Walter agrees and Nina says that it will take time to reconfigure the software. They'll also need to contact their inside man at the ministry, Hastings, to get them a second ecog device.
At the storage facility, Hastings waits in line as Windmark interrogates the staff one by one. He receives a call and cancels it, unaware that it's from Olivia.
Olivia, Peter, and Walter pull up outside and try to gain access. When they can't get through the security lock, they call Astrid.
Hastings is called into the office and has no choice but to go in. He admits that he reports indirectly to Nina and Windmark studies him with interest.
Astrid talks Peter through the process to open the locking device. Once it's properly hooked up, they blow out the lock and go inside.
Windmark asks Hastings if he knows about the theft of the sublimation device. When he denies any knowledge, Windmark has his men restrain Hastings and dismiss the other staff members.
The team finds a terminal so they can run a database search and locate the ecog halo in the warehouse. Once they locate it, they get the case and Walter confirms that it has what they need. Meanwhile, Olivia sees Windmark interrogating Hastings.
In the office, Windmark continues telepathically probing Hastings' mind as the engineer tries to deny everything. He begins to crack, admitting that he admires Walter, but insists that he doesn't know where the fugitives can be found.
At the lab, Nina asks Michael to stay in the chair while she goes outside to call Hastings outside of the underground facility. When she does, the loyalists pick up her comm signal.
Olivia calls Nina and warns her that she's been compromised and can't go home. Nina tells Olivia that it's okay and hangs up, and then destroys her comm. Meanwhile, Olivia sees a guard go into the office and then watches as Windmark and the Observers teleport away. As the loyalists go in to remove Hastings, Olivia and Peter break in and shoot them dead. As they free him, Hastings says that Windmark tracked Nina.
Nina goes back to the lab and discovers that Michael has removed the ecog. She assures him that everything will be fine and that there's nothing for Michael to worry about. He steps forward and touches her face, and Nina stares at the boy in shock. After a moment he releases her and looks at the monitors, which show Windmark and his men arriving outside. Nina tells Michael to come with her.
Peter and the others pull up to a checkpoint and realize that they can't backup without drawing attention. They park the car and duck into a nearby parking garage. Peter breaks into a van and hotwires it, and they drive off.
Windmark and the Observers teleport ahead into the black lab. When the loyalist officers come down in the elevator, they fan out to search the place. Nina is waiting for them and greets Windmark, smiling. He demands to know where the fugitives are and she tells the Observer that they're long gone. Windmark realizes that she's blocking her thoughts and warns him that it won't last. As his men continue their search, Windmark finds the cylinder with the dead Observer inside and calls her an animal. He then begins scanning Nina in earnest and picks up images of Michael. Nina asks why Windmark is concerned about him and the Observer dismisses Michael as a curiosity, a genetic anomaly designated XB-6783746. Michael was scheduled for destruction but went missing in the Observers' future time.
When his men report that no one is there, Windmark prepares for a deeper extraction. He asks why Nina isn't frightened and she explains that Observers tilt their head like a lizard to increase the impact of sound on their eardrums. She describes how the Observers have regressed and developed primitive instincts that humans grew beyond, and tells Windmark that he's the animal. Windmark draws back and then orders the loyalists to restrain Nina. As they move in, Nina grabs one of their guns and aims it at Windmark. Smiling, he tells her that she can't hurt him with it. Nina says that she knows and shoots herself in the head.
Sometime later, the team arrives at the lab and cautiously goes inside. They find Nina's corpse and a shocked Walter runs to her, crying. Olivia covers her adoptive mother over, while Walter realizes that the Observers have Michael. Peter notices the surveillance cameras and accesses the footage. They watch as Michael touches Nina and then Nina leaves the main lab with the boy. She then goes back and waits for Windmark, and they watch as Nina kills herself to prevent Windmark from reading her and learning about the plan. They watch as the Observers leave without Michael and start searching for the boy. Olivia finally finds him hiding beneath the dead Observer in the cylinder. He goes to Nina and sheds a single tear.
Back at Harvard, Walter and Michael don the ecog halos and Astrid links them. Walter has Michael touch his nose if he understands him and the boy responds in kind. Next they ask Michael if he remembers meeting Walter and Donald and Michael confirms that he does. Walter asks Michael why he's a vital part of the plan, and Michael removes the ecog halo and steps over to Walter. He touches his face and shares Walter's memories, including September saying that Michael was important and had to live. Finally, Michael brings forth a memory of Walter meeting with Donald: September, before he became an Observer.