The Secret Garden by Frances Hodgson Burnett
Mary Lennox is a ten year old who was born in India her parents were wealthy and had little time for her leaving her to the care of servants she was unaffectionate and sullen. Recently orphaned she was sent back to England to live with an uncle that she had never met who lived in a large manor house. In this house there were many rooms some of which were locked and no one ever entered them. After a while, whilst walking in the grounds she befriends a robin who unearths a key which she finds opens the door to a secret garden sadly neglected- this is not the only secret that she learns about as the story progresses!