The Windmill Thief - Lilly is a captivating children's book that tells the adventures of Lilly and Nikolas in North Holland. During their vacation, the siblings meet their friend Jakob and his family, who introduce them to the beauties of their homeland. From the tulip bloom to the cheese market, and from windmills to climbing dunes, the children experience an exciting time. However, the adventure takes a turn when they learn that Jakob's great-uncle Maarten, the miller, needs help. Someone is stealing the miniature windmills he is making for a museum. Lilly, Nikolas, and their friends are determined to catch the thief while also uncovering a family secret connected to a special recipe and old photographs. This book is not only an exciting story but also a travel guide for families, entertainingly introducing children to the culture and history of the region.