Elizabeth is an eleven-year-old orphan who uses reading and puzzle-solving to cope with her lonely life. Sent away by her unloving aunt and uncle with only three dollars, she arrives at the magnificent Winterhouse Hotel and discovers a place that feels uncannily welcoming. She possesses a strange, fluttery intuition she calls "the feeling," which often precedes unusual physical phenomena like slamming gates or falling objects.

Norbridge is the charismatic, older proprietor of the Winterhouse Hotel. He acts as a benevolent steward of his family's legacy, balancing his administrative duties with a playful, theatrical flair. Despite his cheerful exterior, he exhibits secretive behavior, such as sneaking through the hotel library at night with a flashlight to search for something hidden.

Freddy is a highly intelligent boy staying alone at the hotel while his wealthy parents are away. He finds solace in intellectual pursuits, specifically inventing eco-friendly fuel logs out of walnut shells and solving complex anagrams. Cautious and logical, he acts as a pragmatic counterpart to Elizabeth's impulsive curiosity.

Gracella is Norbridge Falls's estranged twin sister, known primarily through hotel rumors and a locked bedroom at the end of a dark hallway. According to hotel lore, she became fixated on dark magic as a youth and threatened to destroy Winterhouse before running away. Her unsettling legacy casts a shadow over the otherwise joyful hotel.

Marcus is a mysterious guest traveling to Winterhouse with his wife and a massive, coffin-like crate he claims is filled with books. Introducing himself as a bookseller, he is aggressive with the hotel staff and highly protective of his privacy. He quickly attempts to turn Elizabeth against the hotel's owner.

Selena is a woman dressed entirely in black who arrives at Winterhouse alongside her husband. She possesses an unnerving gaze and immediately unsettles Elizabeth by addressing the young girl by name before they are properly introduced. She remains highly protective of their eighth-floor room and its mysterious crate.

Leona is the knowledgeable and friendly librarian at Winterhouse. She presides over a massive, three-story collection of books with gentle authority and a no-nonsense attitude. Accompanied by her talking parakeet, Miles, she provides Elizabeth with a safe, welcoming space to explore her love of reading.

Aunt Purdy is Elizabeth's legal guardian, living in the dreary town of Drere. She is miserly, emotionally cold, and views her niece as an inconvenience. Rather than spending the holidays with Elizabeth, she ships the young girl off to a remote hotel with only three dollars for the journey.

Uncle Burlap is Elizabeth's neglectful guardian who lives with Aunt Purdy. He is complicit in the decision to abandon his ward for three weeks over the Christmas holiday, providing her with minimal resources for her journey to the hotel.

Mr. Wellington is an elderly, eccentric guest spending his holiday at Winterhouse. He dedicates his time to assembling an enormously complex, 35,000-piece jigsaw puzzle of a Himalayan temple. He is immediately impressed when Elizabeth intuitively helps him place a difficult piece.

Mr. Rajput is a long-term guest at the hotel who shares a dedication to the 35,000-piece puzzle in the lobby. He serves as a friendly fixture of the hotel's community and shares snippets of Winterhouse folklore with Elizabeth, adding to her understanding of the strange environment.

Jackson is the friendly head bellhop at the Winterhouse Hotel. He is one of the first staff members to make Elizabeth feel truly welcome, confirming her reservation and assisting her with her sparse luggage. He remains a reliable, helpful presence throughout the hotel's corridors.

Nestor is the historical founder of the Winterhouse Hotel and the grandfather of Norbridge. Though he is long dead, his legacy permeates the building. His portrait holds a hidden secret, depicting him with a book that features lines of coded text, challenging the hotel's observant guests.