"Demon Dentist" is a children's book written by David Walliams. The story follows a young boy named Alfie who discovers that his new dentist is not what she seems. Instead of helping children, she has a sinister plan that involves stealing their teeth. As Alfie and his friends uncover the truth, they must work together to confront the Demon Dentist and save their town from her evil schemes. The book combines humor and adventure, making it an engaging read for children while also addressing themes of friendship and bravery.