A Door to Secrets contains humorous riddles of varying levels of difficulty, making the book accessible to children across a range of reading abilities. Every illustration features the adventurous Watt, who wanders from scene to scene, changing his outfits and activities appropriately. A Door to Secrets is one of thirteen books that make up Independent Reading Level A, for children in Year 3/Primary 4. This phase of Cambridge Reading aims to extend children's experience of fiction, motivate them to enjoy reading and help to improve their independence as readers.