Marly is a sensitive, observant ten-year-old girl who finds intense joy in the natural world. Distressed by her father's lingering trauma from World War II, she desperately hopes that moving to the country will serve as a miracle cure for his depression. She is eager to explore the outdoors but initially lacks the courage to venture away from her family alone. Over time, her curiosity drives her to learn about the plants and animals of the Pennsylvania woods.

Dale is Marly and Joe's father, a World War II veteran who recently returned home after surviving as a prisoner of war. He struggles with depression, anxiety, and a severe sensitivity to sound, prompting the family's relocation to the quiet town of Maple Hill. In the country, he slowly begins to process his trauma by immersing himself in physical labor, home repairs, and gardening.

Mr. Chris is a large, jovial farmer and maple syrup producer who lives near the family's new cottage. He maintains a warm, welcoming demeanor and harbors an infectious passion for the outdoors, particularly the annual sugaring season. He acts as a patient teacher to Marly, introducing her to the native plants and animals while ignoring his wife's concerns about his overexertion.

Joe is Marly's twelve-year-old brother, a highly competitive boy who considers himself a natural explorer. He initially resents leaving his friends and life in the city, frequently vanishing into the woods alone to secure a sense of independence. Over time, he develops a strong interest in homesteading skills and begins gathering wild mushrooms to sell.

Known locally as "Harry the Hermit," Harry is an older, reclusive man who lives alone near a pond, raising goats and crafting wooden chains. Like Dale, he is a former soldier who struggled with sadness after the war, eventually choosing a solitary life off the land. He proves to be a gentle and skilled craftsman who eagerly shares his knowledge with those willing to look past his unkempt appearance.

Lee is Marly and Joe's mother, a steady woman who spent her childhood summers at the Maple Hill cottage with her grandmother. She holds a deep, nostalgic love for the area and orchestrates the family's return there to help her husband recover from his war trauma. She constantly works to manage the household, clean the dusty cottage, and smooth over family tensions.

Chrissie is Mr. Chris's wife, a hospitable woman who easily welcomes Lee's family into her farm kitchen. She is a talented cook who frequently worries about her husband's tendency to work too hard, especially given his diagnosed heart condition. She provides immediate maternal care to the newly arrived city family.

Fritz is the hired caretaker who assists Mr. Chris with the heavy labor on his farm, particularly during the demanding sugaring season. He is a reliable presence who soon becomes a trusted associate of Marly's family, often taking Dale and Joe fishing during their breaks from work.

Miss Annie Nelson is the local school nurse and truancy officer, affectionately nicknamed "Annie Get Your Gun" due to her strict enforcement of attendance. Despite her rigid official role, she proves open-minded and becomes deeply fascinated by the practical educational value of maple syrup production.

Margie is a local girl who attends the small schoolhouse at Maple Hill. She quickly befriends Marly, easing her transition into the rural community, while her older brothers help teach Joe how to forage safely in the woods.

Grandma is Lee's late grandmother, whose spirit and memory loom large over the Maple Hill cottage. Though she is no longer living, her legacy of sweeping children outdoors to enjoy nature heavily influences Lee's parenting and Marly's expectations of the country.