"De brief voor de koning" is a Dutch children's book written by Tonke Dragt. The story follows a young squire named Tiuri who embarks on a dangerous quest to deliver a secret letter to the king. Along the way, he faces various challenges and meets different characters, testing his bravery and loyalty. The book, first published in 1962, has become a classic in Dutch literature. It has been translated into multiple languages and adapted into a film and stage productions. The themes of adventure, friendship, and courage resonate with readers of all ages.