King & Kayla and the Case of the Secret CodeBy: Dori Hillestad Butler Illustrator: Nancy Meyers Series: King & Kayla King & Kayla are back on the case in this laugh out loud mystery from the Theodor Seuss Geisel Honor Award winning series. King and Kayla receive a mysterious letter written in code. Mason received an almost identical letter. How can they crack the code? Kayla notices that there aren't any vowels in most of the words; you can't write words without vowels. When she compares her