"There are a few things you should know about Harriet Wermer: She just finished third grade. She has a perfect cat named Matzo Ball. She doesn't always tell the truth. She is very happy to be spending summer vacation away from home and her mom and dad and all the wonderful things she had been planning all year. Okay, maybe that last one isn't entirely the truth. Of course, there's nothing Harriet doesn't like about Marble Island, the small island...