When a little boy asks a powerful king, "Why do we have shadows?" the ruler doesn't know---and neither do his wise men. But then the king hears about somebody who's so great that he's only light, with no darkness---and no shadow! A wonderful story about the holiness of God for your 4- to 8-year-olds! 32 pages, hardcover from P & R.
This is not a simple storybook as it contains truths about God being a holy and glorious God. Kids who are more mature, probably at least 7 years old might be able to benefit from this. It is not easy to find theologically sound books. This is one of them.