The novel centres on Mary Lennox, who is living in India with her wealthy British family. She is a selfish and disagreeable 10-year-old girl who has been spoiled by her servants and neglected by her unloving parents. When a cholera epidemic kills her parents and the servants, Mary is orphaned. After a brief stay with the family of an English clergyman, she is sent to England to live with a widowed uncle, Archibald Craven, at his huge Yorkshire estate, Misselthwaite Manor. Her uncle is rarely at Misselthwaite, however. Mary is brought to the estate by the head housekeeper, the fastidious Mrs. Medlock, who shuts her into a room and tells her not to explore the house.
Mary is put off when she finds that the chambermaid, Martha, is not as servile as the servants in India. But she is intrigued by Martha’s stories about her own family, particularly those about her 12-year-old brother, Dickon, who has a nearly magical way with animals. When Martha mentions the late Mrs. Craven’s walled garden, which was locked 10 years earlier by the uncle upon his wife’s death, Mary is determined to find it. She spends the next few weeks wandering the grounds and talking to the elderly gardener, Ben Weatherstaff. One day, while following a friendly robin, Mary discovers an old key that she thinks may open the locked garden. Shortly thereafter, she spots the door in the garden wall, and she lets herself into the secret garden. She finds that it is overgrown with dormant rose bushes and vines (it is winter), but she spots some green shoots, and she begins clearing and weeding in that area.
Mary continues to tend the garden. Her interaction with nature spurs a transformation: she becomes kinder, more considerate, and outgoing. One day she encounters Dickon, and he begins helping her in the secret garden. Mary later uncovers the source of the strange sounds she has been hearing in the mansion: they are the cries of her supposedly sick and crippled 10-year-old cousin, her uncle’s son Colin, who has been confined to the house and tended to by servants. He and Mary become friends, and she discovers that Colin does not have a spinal deformation, as he has believed. Dickon and Mary take Colin to see the garden, and there he discovers that he is able to stand. The three children explore the garden together and plant seeds to revitalize it, and through their friendship and interactions with nature they grow healthier and happier. When her uncle returns and sees the amazing transformation that has occurred to his son and his formerly abandoned garden now in bloom, he embraces his family, as well as their rejuvenated outlook on life.
