Kevin, who goes by Bern, is a dedicated musicology professor at the University of Virginia and a leading expert on the composer Frederick Delaney. Growing up in a lower-class family in Milwaukee, his life changed when the Delaney Foundation gifted him a French horn, making him a loyal "DF Kid." He is passionate, meticulously observant, and deeply respectful of musical history, though his reverence for his idols occasionally blinds him to institutional flaws.

Josephine is a brilliantly talented, neurodivergent Black musician living in New York City during the 1920s. She possesses perfect pitch and synesthesia, experiencing sounds as vibrant colors, shapes, and physical textures. To cope with the overwhelming sensory input of the city, she transcribes the world's sounds using her own unique system of musical notation called the Compendium.

Frederick is a white, Midwestern musician who arrives in New York City in the 1920s with dreams of musical stardom. Initially struggling to keep his place in a local jazz band, his trajectory shifts dramatically after he meets Josephine Reed and discovers her extraordinary talent. He is highly ambitious, deeply concerned with his public image, and eager to secure wealth and status in the competitive music publishing industry.

Eboni is a brilliant cybersecurity expert and computer analyst who originally met Bern when they were graduate students at Columbia. She hides a warm, compassionate nature beneath a tough, no-nonsense exterior and is deeply skeptical of elite institutions. Her formidable hacking skills and digital expertise are vital to decoding historical mysteries.

Mallory is the executive director of the Delaney Foundation and a direct descendant of Frederick Delaney. Polished, highly educated, and wealthy, she is dedicated to preserving her family's prestigious musical legacy. While she initially appears supportive of Bern's academic work, she is fiercely protective of the Foundation's secrets and reputation.

Kurt is a powerful and influential board member of the Delaney Foundation, sharing his ancestor's famous surname. He is heavily invested in maintaining the pristine image of the Foundation and retaining strict control over its assets. Accustomed to unquestioned authority, he uses his wealth and institutional power to intimidate anyone who threatens his organization's narrative.

John Ditmars is the pragmatic owner of Ditmars & Ross, a successful music publishing company in the 1920s. He hires Frederick Delaney as a song plugger to play and promote his sheet music in department stores. Driven entirely by profit, he is highly skeptical of new talent and holds strict, discriminatory views about who belongs in his offices.

Miles is a tall, serious composer who initially works for Ditmars & Ross before launching his own rival music publishing house. He is a savvy businessman in the 1920s music scene who recognizes the market value of a good song, though his business decisions are heavily influenced by the pervasive discrimination of the era.

Earlene is Josephine Reed's cousin, living in the old Reed family home in North Carolina. She provides a vital link to Josephine's forgotten history, preserving fragments of her family's past even when the broader academic world has completely overlooked them.

Judy is Earlene's daughter and a descendant of the Reed family. She possesses an excellent memory for the objects stored in her family's home and points the researchers toward a forgotten steamer trunk in the basement.

Eunice is the perky, redheaded receptionist at the Ditmars & Ross publishing house in the 1920s. Unlike many of her peers, she is relatively open-minded and kind, offering Josephine practical help and emotional support when she struggles to adapt to the noisy office environment.

Jacques Simon is Bern's late academic advisor and a former professor at Columbia University. A highly respected scholar of Frederick Delaney's music, his past work laid the foundation for Bern's current career and his deep reverence for historical musical analysis.

Stephanie is an employee at the Delaney Foundation assigned to assist Bern with his intensive research project. She helps manage his logistics, housing, and document access as he works within the high-pressure environment of the Foundation.

Samantha is the granddaughter of John Ditmars, the 1920s music publisher. She has preserved her grandfather's corporate archives in her Yonkers home, inadvertently holding the key to decades-old secrets about the publishing industry.

Whitman is the chief legal counsel for the Delaney Foundation. He is a strict, meticulous lawyer whose primary job is to enforce the organization's ironclad nondisclosure agreements and protect the Foundation from any liability or public scandal.

Mona is a reporter for the New York Times and a media contact of Eboni's. She is initially intrigued by the possibility of exposing a major historical fraud, though she must carefully balance the allure of a breaking story against the heavy legal risks associated with corporate whistleblowing.

Lauren is a sharp, capable lawyer hired by Bern and Eboni to help them combat the Delaney Foundation's aggressive legal tactics. She provides crucial strategic advice as they prepare to challenge the powerful institution.

Detective Kirdahi is a police officer who detains and interrogates Bern regarding alleged stolen property from the Delaney Foundation. He is dismissive of Bern's rights and fully cooperative with the Foundation's heavy-handed tactics.