As Doc follows at a discreet distance, Hauser makes a late night visit to Chinatown, where he's treated for an unspecified ailment with herbal remedies and a massage. Hauser's memories drift back to 1960, where as a young Alcatraz prison guard he walks hand in hand with Lucy. As they talk, he reveals his background studying philosophy. Then they make plans to see each other again.
Warden James praises Lucy's accomplishments with various prisoners as he introduces a new challenge: Webb Porter, a man with a genius level IQ. Porter is being kept in an infirmary cell because he won't stop screaming in the standard prison blocks. Porter's mother attempted to drown him in a bathtub when he was a child, leading him to later kill her, along with a string of subsequent female victims.
Lucy discovers Porter with his ear pressed against the wall after continually dragging his cot alongside it. She quickly surmises that he suffers from tinnitus, a constant ringing in his ears likely caused by his near-drowning. The hum of refrigerator on the opposite side of the wall apparently soothes him. She suggests a musical treatment.
In the present day, Porter plays a violin beautifully but aggressively. He ultimately breaks the instrument's strings with his intensity. He then draws a bath and puts the violin in its case. As he does so, it's revealed that he has taken a woman prisoner and is keeping her bound and gagged on a bed. He studies her crudely close-cropped hair a moment, wishing she had more, and apologizes to her before dragging her into the bathroom where he drowns her.
Rebecca and Nikki shoot pool and knock back beers at a local bar. Rebecca tries to explain to her friend how she'd like to go back to the life she led before joining the task force, but she feels that she can't. Then Rebecca gets a call from Doc, whom she scolds for continuing to follow Hauser. Doc says that he left Hauser to visit the comatose Lucy in the hospital - despite Hauser's earlier admonitions not to visit and let her rest - only to find her gone. Now he's waiting for the complete story from the staff.
Nikki also gets a call, summoning her to the crime scene with the drowned woman, and Rebecca tags along. At the crime scene, Nikki determines that the woman, a music student named Karen, had been held captive for three days, and Rebecca wonders if her hair had been kept as a souvenir by her killer. Rebecca finds a broken fingernail and gives it to Nikki to search for the culprit's DNA.
As Rebecca and Doc try to find a connection to the '63s, Hauser surprises them and warns Doc: "If you ever follow me again, I may decide to shoot you after all." He tells them what he's done with Lucy is none of their business. The revelation of colloidal silver in the blood sample alerts Hauser that the culprit is indeed one of the '63s, and one that's not in the database - they don't know who they're after.
Rebecca and Doc question Karen's music instructor, who doesn't recognize any photos of the known '63s. Meanwhile, Hauser orders Dr. Beauregard to study the blood sample in hopes of using the colloidal silver's healing properties to save Lucy, whom Beauregard reveals is quickly slipping further and further away.
Back in 1960, Lucy works to remove Porter's painful memories by pushing him to bring musical melodies into his head to help keep him calm. Porter is agitated at first, but the music does eventually soothe him. He recalls his near-death at his mother's hands. He'd been struck by the beauty of his mother's face while she tried to drown him as her long hair floated atop the surface of the water. Lucy says that she believes she can help Porter to heal.
In the present day, Porter plays his violin on the front porch of the home of a woman he met at a party, and though his explanation of how the music came from his head begins to unnerve her, he manages to overpower her and take her captive, telling her, "I like your hair."
Dr. Beauregard tells Hauser that the mystery '63's blood is a match with that of Lucy; if Hauser can capture him, Lucy has a chance.
Meanwhile, Porter plays at a music audition and is praised by the panel. He tells them that he strings his violin himself, which he believes makes a difference. He's asked to play another piece of music to gauge his sight-reading, and when his hesitation suggests that he can't actually read music, he's dismissed. Distraught, he returns home and expresses his frustration to his most recent victim, who is bound and gagged with her hair shorn on the bed, and he quickly makes her the focus of his rage.
In 1960, Lucy brings Porter into a rehearsal session by the prison's jazz band, overseen by assistant warden Tiller. Neither Tiller nor the band of inmates is pleased to have Porter there, and the session is ended. Tiller professes his love of music. He says that he had been discouraged by his father, and he came to it late in life.
Lucy wants to borrow an instrument to further Porter's therapy, and he's drawn to the violin. Lucy suggests that he play what's in his head, and Porter quickly demonstrates an instinctive skill with the instrument. Tiller thinks Porter has been feigning inexperience, but Lucy tells him that Porter is a savant.
When Porter's latest victim is discovered, an impatient Hauser blows up at Rebecca, suggesting that she's been wasting time following false leads with "boring people." Doc informs them that the landlord heard violin music earlier at the crime scene, and the new victim has no musical ability.
Hauser realizes that the culprit isn't targeting musicians as they had suspected but actually IS a musician himself. Doc and Rebecca then scour the prison's musical archive, discovering a violin with the name "Webb Porter" carved into its side.
As Rebecca and Doc search for a pattern of clues in Porter's killings, Hauser makes a visit to Ratty's Jazz Bar to see a blues pianist named Elmore, who's familiar with every musician in the city. When Hauser describes a young violinist who plays music from out of his head, Elmore makes a connection and puts Hauser on the trail. The kid he's thinking of got a job as a stagehand at the Philharmonic.
In 1960, young Hauser and Lucy enjoy the show at the same jazz bar, where Lucy wishes she could bottle the music to bring back to Porter. Hauser's amused at how Lucy can see a "patient" in what others view as "a stone-cold killer," but she's pleased with the rapid progress Porter has demonstrated. Hauser's enchanted by her passion, and they kiss.
Rebecca and Doc track both victims to an event at the Philharmonic, just as Hauser passes his information about Porter on to them. Searching Porter's apartment, they realize that he's been there for a few months, meaning that the '63s are settling in to their new world.
Then Hauser makes a chilling discovery: Porter is using his victims' hair to string his violin bows, and the presence of a bow with red hair reveals that he's taken a third woman.
With his latest victim tied and gagged, Porter explains to her that she has enough hair left to string his bow.
In 1960, Lucy tells Porter that he's ready to be placed back into the general population, where he can keep his violin and play at the end of each day. Porter questions why Lucy's doing so much for him, and she tells him that she believes that a man can change. He tells her that maybe one day he can repay her.
The task force narrows the possible victims down to two redheads, and when a social network check-in eliminates one possibility, they zero in on the remaining woman's home, where they discover her tied on the bed. She tells them that Porter succeeded at an audition, and he's making his debut performance. Onstage, Porter plays with skill and passion, receiving an enthusiastic ovation.
In 1960, when Porter is placed back into a regular cellblock, his fellow prisoners object vehemently, but he is able to quiet the protests as he plays his instrument. As Tiller, Beauregard, and Lucy marvel at the sudden shift, Beauregard suggests that Warden James has found a new toy. When Lucy objects that Porter isn't a toy, Beauregard corrects her: "I was talking about you."
As Porter packs up his violin, Hauser and Rebecca storm the empty concert hall. After a lengthy backstage chase, they corner Porter in the catwalks above the stage. Porter tries to leap over the railing, but Hauser snags him and pulls him back onto the catwalk, cuffing him.
At the secret facility, Hauser brings Porter into the room where Lucy lies comatose. When Porter asks if Lucy will live, Hauser tells him, "With your help." Dr. Beauregard uncuffs him and prepares to draw his blood as Hauser takes Lucy's hand in his.
Doc digitizes footage they discovered of the Alcatraz jazz band, although it lacks sound. He and Rebecca spot Lucy in the footage, and they realize that she's one of the '63s and could be the key to the mystery. Meanwhile, Porter plays his violin from his new cell as Hauser and Beauregard await some sign of hope from Lucy as her blood is transfused. Suddenly her eyes open.