Charley's lowercase letters have a big problem. Little x is missing, and the rest of the alphabet cannot complete their daily tasks without him. Upset that he is hardly ever used, little x has run away to the mysterious castle of Master M. The other letters bravely set off on a rescue mission, but they soon find themselves in trouble. Master M wants to turn them all into alphabet soup! It is up to little x to use some quick thinking to save his friends and prove that every letter is important, no matter how rarely they are used. This clever mystery brings the alphabet to life through a fun and exciting adventure. Young readers can follow along as the letters work together to escape the castle and make it home just in time to bake a special surprise for Mom.