Zoe is a 10-year-old girl with grand dreams of becoming a star pianist and playing at Carnegie Hall like her historical hero, Vladimir Horowitz. Instead of a grand piano, she receives a Perfectone D-60 electric organ, which deeply disappoints her. She has a vivid imagination and often feels out of place with her peers at school. She tries to maintain family harmony while quietly managing her parents' unique quirks.

Zoe's father is a caring but anxious man who struggles to leave his house due to severe public anxiety. He spends his days taking mail-order classes from "Living Room University" and making impulsive purchases. He accidentally buys Zoe the electric organ after getting distracted by a salesman playing a rumba beat at the mall.

Zoe's mother is a fiscal controller for the state of Michigan. She works long hours and is rarely home, leaving Zoe feeling disconnected from her daily life. She bonds with Zoe primarily during car rides when they listen to classical music on the radio.

Mabelline is an organ teacher who insists on comfort and a glass of ginger ale during her lessons. She is strict and immediately deflates Zoe's hopes of being declared an instant prodigy. She expects hard work and steady practice from her students.

Emma is Zoe's best friend from third grade, though they rarely socialize outside of school. She comes from a wealthy family and usually gets whatever she wants. She is beginning to outgrow Zoe, adopting new trends and befriending other girls.

Wheeler is a tough-looking classmate known for wearing the same jean jacket and having messy dark hair. Most students are afraid of him, but he surprises Zoe by acting friendly toward her and complimenting her music.

Mona is an 11-year-old girl who also takes organ lessons from Mabelline Person. She is highly experienced with musical competitions and approaches playing with passion rather than anxiety. She offers practical advice to other musicians.

Vladimir Horowitz is a famous historical Russian-American pianist and Zoe's personal hero. She idealizes him as a child prodigy and uses his career trajectory as the standard for her own musical dreams.

Colton is a boy in Zoe's class. He sits at the lunch table with the rowdy boys but shows quiet, awkward signs of having a crush on Zoe.

Hugh is the UPS delivery driver who brings Zoe's father his mail-order courses. He frequently stops in for coffee and shares strange stories about his other delivery customers.

Lester is a cut-rate music teacher from "More for Les" who teaches piano using paper keyboards instead of real instruments. He claims his method offers a worry-free way to practice.

Mr. Perfectone is the slick organ salesman who spots Zoe's father dancing to the music at the mall. He easily talks Zoe's father into purchasing the Perfectone D-60 electric organ instead of a piano.