Ben is a young boy living in Gunflint Lake, Minnesota, who recently lost his mother in a car accident. Initially deaf in one ear, a lightning strike leaves him completely deaf, further isolating him from his relatives. He curates a small museum box of objects that represent his memories. Driven by a clue found in his mother's belongings, he travels to New York City to search for a man named Daniel, hoping this stranger is his missing father.

Rose is a deaf and mute adolescent girl living in Hoboken, New Jersey, in 1927. She feels misunderstood by her distant father and resents her tutor's attempts to force her to read lips. Deeply visually oriented, she relies on silent films and scrapbooking to connect with the world. Frustrated by the lack of support at home, she runs away to New York City seeking attention and care from her mother.

Elaine is Ben's late mother, who worked as a librarian in Gunflint Lake. Independent and passionate about books, she raised Ben alone and encouraged him to be brave and curious. Her recent death in a car crash leaves Ben searching for answers about his past, guided by a mysterious bookmark she kept hidden in a book about museums.

Jamie is a curly-haired boy who spends his summers in New York City with his father, who works at the American Museum of Natural History. Lonely due to his parents' separation and his father's busy schedule, Jamie takes an immediate interest in Ben. He is a creative photographer who collects polaroids and offers Ben a place to stay inside an unused museum storage room.

Walter is Rose's older brother who works at the American Museum of Natural History in New York City. Kind and sensitive to his sister's needs, he offers her a safe haven when she runs away from their unhappy home in Hoboken. He shares a love of books with Rose and actively supports her well-being.

Daniel is a man who once visited Gunflint Lake on a research trip for a museum exhibit. Ben finds Daniel's name and old New York City address on a bookstore bookmark tucked inside his mother's belongings. This discovery makes Daniel the central focus of Ben's journey to New York, as Ben hopes the man is his missing father.

Janet is Ben's older cousin, living in Gunflint Lake. She bears a strong physical resemblance to Ben's mother, Elaine, and Aunt Jenny. Unlike others in the family, Janet openly expresses her grief over Elaine's death, providing Ben with a rare source of empathy and comfort during his mourning.

Lillian is a famous stage and silent film actress working in New York City. She left her family in New Jersey to pursue her theatrical ambitions, leaving her daughter Rose behind. When Rose tracks her down at a Broadway rehearsal, Lillian reacts with frustration rather than warmth, prioritizing her career over her maternal duties.

Aunt Jenny is Elaine's sister and Ben's aunt. Following her sister's fatal car accident, she takes Ben into her home in Gunflint Lake. She is a caring, practical woman who worries deeply about Ben's well-being, especially after he is struck by lightning and loses the rest of his hearing.

Robby is Ben's cousin who shares a bedroom with him after Ben moves in with his aunt and uncle. He is often impatient and dismissive of Ben, mocking him for his partial deafness and showing little understanding for Ben's grief or his collection of objects.

Uncle Steve is Ben's uncle by marriage. He lives in Gunflint Lake and helps manage the practical aftermath of Elaine's death, including financial matters regarding her estate and Ben's housing situation.