An orphaned girl changes the lives of those she encounters at a remote estate.

Mary Lennox, a spoiled young English girl living in India at the turn of the century, is orphaned when her parents die of cholera, and is sent to Yorkshire to live with her wealthy uncle, Archibald Craven. Mrs. Medlock, Craven's cruel and ill-tempered housekeeper, meets Mary at the port and escorts her to her uncle's eerie mansion. Craven refuses to meet Mary, and Mrs. Medlock warns her against snooping around the darkened house. When Mary asks about the screams she hears from another part of the house, Mrs. Medlock locks in her room for the rest of the night. The next morning, Mary meets Martha, a maid who laughs incessantly and who refuses to obey her commands. Mary later befriends Martha's young brother Dickon, who tells her that there is a secret, locked garden on the estate, and that Craven buried the key to it. Mary finally meets Craven just before he sets out on a trip to London, and during her brief meeting with him, she learns that his wife was crushed to death by a tree limb ten years earlier. Soon after Craven leaves, Mary sees a raven digging for worms outside the house and notices that the bird has unearthed the buried key to the secret garden. Late that night, while investigating the source of the mysterious screams in the house, Mary discovers Craven's young son Colin. Colin, who is bedridden and is being treated by a doctor for paralysis, admits to the tantrums and demands that Mary obey his orders. Mary, however, refuses to indulge Colin and eventually wins his respect and friendship. The following day, Mary and Dickon discover the entrance to the garden behind some bushes, and use the key to open the gate. Once inside, Mary and Dickon find a neglected garden containing a variety of pretty flowers. They also find a fallen tree limb on a chair next to a table that was once set for tea, and realize that they have discovered the place where Craven's wife was accidentally killed. Later, Mary introduces Colin to Dickon, and tells him stories about their visits to the secret garden. One day, a new doctor, Dr. Fortescue, examines Colin and determines that he is suffering from nothing more than fear, and suggests that the irons placed on his legs by the previous doctor be removed. Dickon and Mary later take Colin in a wheelchair to the secret garden and show him all the flowers they have been growing. Excited, Colin attempts to stand up on his own but falls. Later, when Craven returns from London, Fortescue accuses him of wallowing in his grief and transferring his longing to die to his son, thus causing Colin's physical deterioration. Craven angrily rejects Fortescue's accusation, and announces that he will be selling the estate and moving to Italy with Colin. Craven later has a change of heart, however, when he enters the garden and sees Colin rise from his wheelchair to walk toward him. Astounded at Colin's sudden ability to walk, Craven embraces his son and decides to remain at the house.