Richard is a 45-year-old concert pianist living in Boston. Accustomed to a successful and demanding career, he receives a sudden diagnosis of amyotrophic lateral sclerosis. He struggles with the progressive loss of his motor control starting with his right hand. This physical decline immediately threatens his career and forces him to reevaluate his isolated personal life.

Karina is a Polish immigrant and classical piano teacher living in the house she once shared with her ex-husband. She previously abandoned her dreams of playing jazz music to raise her daughter and support Richard's career. She harbors lingering resentment over their divorce and his past betrayals but remains deeply affected by his declining health.

Grace is an athletic freshman at the University of Chicago. She feels a closer connection to her mother and remains largely estranged from her father. She resents Richard for his absence during her childhood and feels betrayed when her parents withhold information about his health.

Bill is Richard's primary home health aide. Having previously cared for his late partner, he brings an upbeat and flamboyant energy to his daily work. He refuses to indulge in pity, providing his patients with excellent physical care and necessary emotional grounding.

Elise is a professor of contemporary improvisation at the Berklee College of Music and Karina's neighbor. As a breast cancer survivor, she actively encourages her friend to step outside her comfort zone and re-engage with jazz music.

Walt is Richard's estranged father. As a dedicated athlete and coach from rural New Hampshire, he showed no interest in Richard's affinity for classical music. He directed his attention toward his more athletic sons.

Tommy is one of Richard's brothers. Raised in New Hampshire, he shares his father's athletic interests but maintains a connection with his siblings. He currently houses the family piano for his own children to use.

Mikey is Richard's brother. He attempts to encourage Richard to fight his illness using well-intentioned references to sports documentaries and viral social media challenges.

Kathy is the care coordinator at the local ALS clinic. She conducts regular exams to track Richard's symptoms and offers practical advice for managing his declining mobility. She actively encourages him to seek support from his family.

Dr. George is an augmentative communications specialist. He assists Richard in preserving his voice and provides tools to help him communicate as his symptoms progress.

Maxine is a woman Richard dates shortly after his diagnosis. He initially hides his condition from her until the physical and emotional toll becomes impossible to conceal.

Matt is Grace's college boyfriend at the University of Chicago. He meets Karina during a family weekend visit, where they bond over discussions of musical talent.

Dylan is a 13-year-old piano student of Karina's. He struggles with simple preludes during his lessons, reflecting her growing frustration with teaching.

Mr. Borowitz is Karina's former piano teacher in Poland. He instructed her in the classical repertoire of Frédéric Chopin.

Sandy is Richard's deceased mother. She supported his musical aspirations during his childhood and protected his instrument from his father's anger.

Melanie is one of Richard's home health aides. She takes over the shift immediately following Bill's morning routine.

Pam is the host of a graduation party in Boston. She accidentally reveals Richard's diagnosis to Karina during the event.

Alexander is an up-and-coming jazz pianist. He performs at a bistro in New Orleans, and his playing profoundly affects Karina during her trip.