From the former Children's Laureate and twice winner of the Kate Greenaway Medal comes a stunning and perceptive story about worry and anxiety, featuring his much loved chimp, Willy. One day Willy goes to the park. It's a sunny day, but a cloud hovers over him and he can't join in the fun. What can Willy do to make this mysterious cloud go away? Exceptional illustrations combined with the insightful story makes this an essential book for young children.