The Secret Garden: A Graphic Novel #1

Spoiled orphan Mary lives with her reclusive uncle in a huge, mostly-empty mansion. She discovers a neglected walled-up garden and begins to tend it in secret with Dickon's help. When she discovers an invalid cousin, she brings him in on the secret. The children thrive, opening the heart of Mr. Craven, who had walled up the garden after the death of his wife.