2She's smart as a whip, super sleuth-y, and able to solve most mysterious mysteries and perplexing problems in no time flat. Mariella Mystery (age nine and a bit) knows that all good detectives write down important information about their investigations. In this top-secret journal she tackles the case of the ghostly guinea pig with important clues and observations, helpful drawings, and handy tips for new detectives. Early readers will be hooked on this mystery chapter book from page one