Twelve-year-old Kate and her younger sister, Joss, are close friends-which is unusual, because the two of them are completely different. Thoughtful Kate plans to be a writer someday, while bubbly Joss makes friends wherever she goes. This promises to be their best summer yet, because Joss is going to rent a horse for the week of her eleventh birthday. Although Kate is excited, she somehow feels that they are almost too happy-that something bad is...