David considers whether the voices he hears might be real.
The episode opens with a montage of David Haller's life to the song of Happy Jack by the Who. We see David go from a sweet toddler to a troubled youth to an aggressive and drug addicted teen. We see David tormented by voices and people only he can see. We then see David diagnosed with Schizophrenia and given medication. Next we see David in his twenties-thirties attempting suicide.
The scene then cuts to Amy, David's sister, singing happy birthday to him. We learn David is now living in a mental institution called Clockworks Psychiatric Hospital and has been for the past 6 years. Now in his early 30s, David loses himself in the rhythm of the structured regimen of life in the hospital: breakfast, lunch, dinner, therapy, medications, sleep. David spends the rest of his time in companionable silence alongside his chatterbox friend Lenny Busker, a fellow patient whose life-long drug and alcohol addiction has done nothing to quell her boundless optimism that her luck is about to change.
The pleasant numbness of David's routine is completely upended with the arrival of a beautiful and troubled new patient named Sydney (Syd) Barrett. David immediately developed an attraction to Syd, and they began dating. Mysteriously, Syd refused to allow anyone to touch her in any way, not even her new boyfriend. The two grow close despite the lack of physical contact.
One night Sydney sneaks into David's room where they lie on the bed enjoying one another's company. Sydney then tells David that Dr. Dennis Kissinger, their therapist, believes Sydney has recovered and she'll be released tomorrow. Syd tells David that he needs to get better too so they can be together outside of the hospital. This upsets David and he tries to kiss her hand but she pulls it away before he can.
The day of her release, Syd and Dr. Kissinger wait for David to arrive and say goodbye but he never shows. Dr. Kissinger says that this is probably for the best and begins to lead Sydney out of the building. As Sydney's leaving David, sprints into the dayroom and impulsively kisses her. As their lips meet a shock wave is sent out and the two fall backwards onto the floor. David begins to panic, screaming for Sydney to stop while several nurses hold him down. Sydney appears to be disoriented and Dr. Kissinger helps her up while telling David to stay away, he then takes Sydney out of the room. In the dayroom, David continues to panic. A crowd of patients and nurses has now gathered around him and Lenny attempts to help everyone calm down but to no avail. Suddenly the room becomes pitch black and deadly silent, interspersed with flashes of red light that flood the room. The nurses have now released David and the crowd has turned their backs to him. In between the flashes of light a large, looming figure, only known as the Devil with the Yellow Eyes, is seen in the crowd.
During this event, Dr. Kissinger took Sydney to a side room where he treated her for any injuries that might of occurred. While doing so the entire building shakes and a loud "Boom" was heard. Kissinger then tells Sydney to stay put before leaving to investigate the sound. After Dr. Kissinger leaves, Sydney looks into the mirror and the audience discovers that when Syd and David kissed they swapped bodies. David, in Syd's body was taken to the side room and treated by Dr. Kissinger, while Sydney in David's body panicked in the dayroom.
David quickly follows Dr. Kissinger out side room and back to the dayroom where they find all the furniture and doors to be gone. They then discover all the patients are trapped in their rooms and Lenny in a wall, dead. Shocked by this David (in Syd's body) leans against a wall only to hear Syd (in David's body) calling for him on the other side. The audience learns that David also has powers and when Sydney and him traded places, Sydney accidentally set them off causing the event.
Dr. Kissinger then released David (still in Syd's body) from Clockworks, believing that Sydney would not get another chance to be released after the chaos died down. As Syd, he was escorted from Clockworks. Just before leaving, he spotted a mysterious car which slowly back up to Clockworks. The three passengers of the car then get out. Two of the passengers are a man and woman about David's age.
Not wanting to see what these people wanted, David quickly leave's Clockwork's property. He went into the city and stopped at an outdoor cafe where his own body returned to him. Needing a place to stay for the night, David goes to his sister's house. She agreed to let him stay for a few days with Ben, her husband, and her. Amy showed him to the spare bedroom in the basement.
While unpacking David hallucinated Lenny who began a light hearted conversation with him which quickly becomes melancholic as he remembers she's dead. Lenny tells David that it's okay that she's dead because living the rest of her life in a mental hospital wasn't a life worth living. She also tells David that it is his fault she's dead. When he begins to protest that it was Syd using his powers, she retorts, "Don't give a newbie a bazooka and act surprised when she blows shit up.” Lenny then gleefully warns David that "They're coming and they're going to kill you!" Justifiably this scares David and he accidentally telekineticly throws his childhood lamp across the room. Amy comes down stairs after hearing the noise and sees David picking up the pieces of the lamp, worried about her brother and her own safety she removes the gardening tools from the basement.
After taping the lamp back together David dreams about Sydney and the next morning becomes determined to find her. David goes to a pay phone and calls Clockworks inquiring about Sydeny only to be told she is not a patient there and never was. Before he can find out more the man and woman from car appear and begin to follow him. David is able to lose them in a busy plaza but right after is abducted by man with a milky eye and several Government agents. The agents drug him and pull him into a van.
David then wakes up in a room where two men, Clark and Walter, sit across from him. They lie and tell David that they're with the police and want to get his statement about what occurred at Clockworks. Walter is the man with the milky eye from the van and doesn't talk throughout the questioning. Clark does all of the talking while Walter works on a carving a wooden statue. David re-accounts his story but becomes upset when he thinks Clark doesn't believe him about certain aspects such as the body swapping causing his powers to start shaking the pen that Clark was using to take notes. David then asks to take a break which Clark allows saying that lunch will be sent in momentarily. Clark then leaves the room and Walter sits across from David. David asks to be alone and Walter places the wooden statue of the dog he was carving on the table before leaving.
As the audience follows Clark out of the room, we learn that it is a mock room built to look like a interview room. Outside of where David is being held is a pool as well as a theater. The building is swarming with people who are moving objects, talking, cleaning guns, etc. Clark then walks up a set of stairs to a room where his commander, Brubaker, is.
Clark calms him down and they hook David up to some machines to run tests while he continues. David then remembers that Clark was the third person in the car that arrived out side of Clockworks. Clark tells him that this is not the case which upsets David and he sends the pen flying into Clark's face before destroying the table and sending equipment and people across the room knocking them unconscious. To prevent David from escaping the room is filled with a gas that knocks David out. Brubaker, who was in charge of the operation, wanted to neutralize David before he realized he was a mutant, however Clark pushed for more time to study him. Clark believed David was one of the most powerful mutants in the world and wanted more time to study him.
Clark then returns with several workers and some machines to run tests while David continues his story continues. This irritates David and he asks to see a lawyer before realizing that the workers are afraid of him. Clark lies and says that they're afraid for him, and that David is very sick and they want to see if he is a danger to himself or to others. David accepts this and continues telling his story. David then incorrectly re-accounts that it was Clark and not Melanie who was in the car outside of Clockworks. Clark tells him that this is not the case which upsets David and he sends the pen flying into Clark's face before destroying the table and sending equipment and people across the room knocking them unconscious. To prevent David from escaping, the room is filled with a gas that knocks David out.
When David awoke, he was tied to a chair and power cables in the middle of a swimming pool. Clark demanded to know where Syd was. Stating that they, the people Clark work for, have him but want Sydney too. David continues reluctantly continues telling his tale and that he doesn't know where Sydney is. While recalling his memories, he is met by Syd who was able to project herself into his memories. She confirmed David's suspicions -- these men were not cops at all, but members of Division Three, a secret government agency that targets mutants, and Syd intended to rescue him. She tells him to slowly slide out of his chair and into the water when he sees the lights.
Once he was back in the moment, David looks around the room as he begins to see dancing lights appear in the air. He also remembers that it was not Clark in the car but a older woman. Clark becomes frustrated with David's inability to tell him where Sydney is to which David replies that they're about to find out. Quickly sliding into the water, bullets are shot into the pool and Clark finds the switch to the power cables no longer in his hand right before the entire room explodes in flame. Dodging burnt corpses, David swims to the other end of the pool where Syd pulled him out and introduced him to two of her allies, the passengers of the car at Clockworks - Ptonomy Wallace and Kerry Loudermilk. The four mutants escaped the facility with the aid of Rudy. As they are running to the shore David stops and asks Sydney if any of this is real or if it's a delusion caused by his Schizophrenia. Sydney says that it's all real and that she came back for him because she loves him. David says that he loves her too. They continue running and reach the shore where they are greeted by Dr. Melanie Bird, the older woman from the car at Clockworks. Melanie is the leader of a secret mutant refuge, called "Summerland". She offer's her hand to David. David looks back and sees the Devil with the Yellow Eyes watching him from the bushes before he takes her hand.
- The Devil With The Yellow Eyes appears as one of David's toys in the opening montage.
- Several characters refer to an "incident at Red Hook." Red Hook is the name of the town next to Bard College, where Marvel character Jean Grey was buried. Jean Grey's father was a professor at Bard College and Jean Grey grew up in the area. 
- To depict David Haller losing control of his abilities in a kitchen, actor Dan Stevens was filmed separately from the practical effects, with the images layered together to create the final, slow-motion sequence. 
- During the episode there are various people that only David can see, such as: the old couple when talking to his sister, and the man in the greenery when he's sitting with Lenny. These are not actually delusions and are, in fact, some of David's personalities. 
- When Syd and David switch bodies, she is able to tap into the powers on one of his personalities. Known as Personality #5 in the comics, Personality #5 is a godlike mutant who describes himself as "The One True Legion". He has the ability to warp both time and reality which would explain how Syd was able to change the structure of the patients rooms, leaving no doors, as well as, trapping Lenny in the wall. 
- David is seen in a wheelchair early on in the episode in the hospital. This is a reference to his father in the comics, Professor Xavier.