Mona is a young, orphaned mouse who relies on her wits and speed to survive in Fernwood Forest. When a severe rainstorm floods her hollow stump home, she packs her only family heirloom—a walnut-shell suitcase with a heart carved on the front—and flees into the woods. She accidentally discovers the Heartwood Hotel and pleads for shelter. Granted a temporary position as a maid, she works through the night cleaning the ballroom under strict supervision. Lacking a permanent home, she is highly motivated to prove her worth to the hotel staff and earn her keep through diligent service.

Tilly is a red-furred squirrel who has worked as a maid at the Heartwood Hotel for five years. She wears an apron and carries an oversized broom, managing the daily cleaning routines with strict efficiency. From the moment Mona arrives tracking mud into the kitchen, Tilly is harshly critical, insisting that mice are far too small to work as maids. She enforces the hotel rules rigidly, scolding other staff members for stepping outside their duties and reacting defensively when new workers attempt to alter her established schedules.

Mr. Heartwood is a large badger who owns and operates the prestigious Heartwood Hotel. He wears multiple keys around his neck and often speaks in whimsical, rhyming couplets. He founded the hotel as a sanctuary for traveling animals after wolves took his wife during a journey in the forest. He governs the establishment with a firm commitment to his motto of protection and respect, insisting that the hotel prioritize civilized cooperation over the natural laws of tooth and claw.

Gnarl is the leader of a wolf pack that prowls the dark edges of Fernwood Forest. He wears a stolen mole clubhouse badge around his neck as a trophy. He is arrogant, commanding, and heavily focused on locating the hidden Heartwood Hotel, plotting to use the lights from the upcoming First Snow Festival to guide his pack toward a massive feast of small, vulnerable animals.

Ms. Prickles is the porcupine cook who runs the kitchen at the Heartwood Hotel. She wears an apron and spends her days baking acorn soufflés and familiar, comforting seedcakes for the guests and staff. She acts as a nurturing, maternal figure for the younger employees, immediately offering a dry rag and food when a muddy, freezing mouse arrives at the back door. She possesses a quiet wisdom about the other staff members, recognizing that abrasive behavior usually stems from hidden emotional pain.

Gilles is a lizard who serves as the front-desk clerk for the Heartwood Hotel. He dresses professionally in a bow tie and wears a wooden key to signify his status as a staff member. He is highly protective of the hotel's reputation and eagerly anticipates a visit from a Pinecone Press reviewer. He strictly follows management policies and refuses to perform tasks outside his job description, such as delivering food to guest rooms, believing firmly in the established hierarchy of the hotel staff.

Mrs. Higgins is a round, gray hedgehog who holds the position of head housekeeper at the Heartwood Hotel. She manages the staff schedules and posts daily work lists on her office door detailing room service requests and check-ins. She relies on a cane and carries a handkerchief, currently suffering from a severe cold contracted after a stressful summer dealing with unruly frog guests. Her illness creates a severe staffing shortage that leaves the remaining employees scrambling during the busy autumn season.

Cybele is a timid swallow who books a long-term stay at the hotel through the winter. A storm during the Acorn Festival injured her wing, forcing her to wear a sling and separating her from her migrating flock. She stays in a small, bare room on the upper floors, worrying constantly about her finances and crying in isolation on the stargazing balcony. She possesses a beautiful singing voice, initially performing migration melodies alone before sharing her talents with the rest of the hotel guests.

Brumble is an enormous, elderly bear who wanders into the territory surrounding the Heartwood Hotel. He is forgetful, easily disoriented, and struggling to locate his childhood winter den after the sounds of a wolf pack drove him away from his usual hibernation spot. His sudden arrival outside the hotel's front door causes immense panic among the smaller animal guests, who view his massive size as an immediate threat to their safety.

Lord Sudsbury is a skunk who arrives weeks early at the Heartwood Hotel for his honeymoon. He is highly anxious and suffers from weak nerves, pacing his suite and worrying constantly about the distant howling of wolves in the forest. His nervous disposition causes him to spray when startled, filling his hotel suite with a powerful odor that threatens to get him and his wife evicted from the prestigious establishment.

Lady Sudsbury is a skunk checking into the honeymoon suite alongside her husband. She requests specific accommodations for their stay, including striped sheets, marinated mushrooms, and a tie press. She maintains a composed demeanor, actively trying to soothe her husband's intense anxiety about forest predators. She expects high standards of service from the hotel maids but shows genuine gratitude when the staff successfully manages her husband's nervous accidents.

Wince is a subordinate wolf traveling in Gnarl's pack. He possesses a highly sensitive sense of smell, frequently pausing to investigate the scents of mice and other small creatures hiding in the brush. He is openly skeptical of his leader's strategies, questioning whether the pack's plan to ambush the hotel during the winter festival will actually succeed.

Ms. J is a large emerald-purple June bug who arrives at the hotel seeking lodging. She wears dark glasses and travels with four tiny suitcases. She expects standard hospitality and inquires about accommodations for smaller guests, completely unaware of the hotel management's strict internal rule that bans six-legged creatures from staying on the premises for their own safety.

Mr. Higgins is a portly hedgehog who maintains the private gardens at the Heartwood Hotel. He tends to the flowerbeds and herbs, interacting warmly with the hotel maids when they arrive to collect specific plants for guest requests. He provides the newer staff with sprigs of peppermint to mask unpleasant odors and offers quiet encouragement to help them endure the harsh criticisms of their supervisors.

Tony is a woodpecker employed to act as the primary lookout for the Heartwood Hotel. His job is to monitor the surrounding forest and sound a loud alarm if predators approach the hidden tree. He is easily panicked and occasionally fails in his duties, missing large threats until they are already thumping against the hotel's front door.