The Secret Garden - Frances Hodgson Burnett

After her parents die of cholera in India, Mary Lennox is sent to live with her uncle in his gloomy house in Yorkshire, where she leads a lonely and neglected life, with nothing to do apart from exploring her surroundings. One day she discovers a walled garden which has been locked up, and becomes determined to enter it and find out its secret and the source of the mysterious crying sound that can be heard nearby.