Twelve-year-old Joe Warden isn't happy. He has rich, uncaring parents and is virtually a prisoner in the huge family mansion, Thattlebee Hall. Worst of all, though, is his granny. Not only is she physically repulsive, she's horribly mean. She has the look in her eye of a predatory crocodile and Joe starts to suspect that she has unpleasant designs on him. But what are they and how can he foil them?