Undecided Question

what would you name this book- a man-looking creature who is locked in room of a very rich man's mansion. the man's childhood friend visit's home and think she sees the man in the window so she becomes curious. she sneeks in and takes him home with her, not knowing the mansion is her friend's. she noticed that his skin turns to a stone-looking figure in direct sunlight and he has trmendious strength so she tries to hide him. but, unexpectingly he slowly falls in love with her.
and don't call it beauty and the beast.