The Secret Garden (HarperClassics)

"One of th' gardens is locked up. No one has been in it for ten years."

When orphaned Mary Lennox comes to live at her uncle's great house on the Yorkshire Moors, she finds it full of mysterious secrets. There are nearly one hundred rooms, most of which are locked, and the house is filled with creepy old portraits and suits of armor. Mary rarely sees her uncle, and perhaps most unsettling of all is that at night she hears the sound of someone crying down one of the long corridors.

The gardens surrounding the odd property are Mary's escape and she explores every inch of them—all except for the mysterious walled-in, locked garden. Then one day, Mary discovers a key. Could it open the door to the garden?