Mary Lennox is a sour, unloved nine-year-old girl born in India to British parents who ignore her. When a sudden cholera epidemic wipes out her family and servants, she is left entirely alone before being shipped to Misselthwaite Manor on the Yorkshire moors. Her new guardian, her uncle Archibald Craven, is a grieving hunchback who is almost never at home. The massive house has nearly a hundred locked rooms and sits on the edge of a bleak, wild moor.
Left to herself in this desolate place, Mary's stubborn disposition begins to shift. A cheerful housemaid named Martha introduces her to the local dialect and tells her about the expansive moor and her brother, Dickon, a boy who charms wild animals. Encouraged by the fresh moorland air, Mary begins to explore the massive grounds. She discovers a walled garden that has been locked up for ten years ever since Mrs. Craven died there following an accident on a garden bough, after which her grief-stricken husband buried the key.
Guided by a friendly robin redbreast, Mary eventually finds the buried key, unlocks the garden door, and steps inside. She discovers a tangled wilderness of climbing roses and dormant plants. Eager to restore it, she enlists Dickon to help her secretly revive the space. Working in the soil together brings Mary physical strength, an eager appetite, and a sense of joy she has never known.
While wandering the corridors on a stormy night, Mary hears a faint, fretful crying. Following the sound, she discovers a hidden room and meets her sickly cousin Colin, an invalid boy who has been confined to bed his entire life. Believing he is destined to become a deformed cripple and die young, Colin has been heavily spoiled and prone to terrifying hysterical tantrums. Mary refuses to indulge his self-pity, challenging his fears and proving to him that there is no lump on his spine.
Colin is captivated by Mary's stories of the outside world, Dickon, and particularly the secret garden. When Colin is eventually brought out into the fresh air in his wheeled chair, Dickon pushes him through the secret door into the walled oasis. Surrounded by the vibrant blossoming spring, Colin experiences a miraculous awakening. Standing upright on his own two feet for the very first time, he sheds his lifelong invalidism and declares that he will live forever. The garden becomes a sanctuary of rebirth for the children, while old Ben Weatherstaff and the domestic staff bear witness to the profound physical and emotional healing taking place behind the ivy-covered walls.
