Book excerpt: Fans of Dav Pilkey's The Adventure of Ook and Gluke and Patricia Reilly Giff's ZigZag Kids series will flock to this chapter book series full of slapstick humor and silly situations by the wildly popular Tony Abbott, author of The Secrets of Droon Series. When the Goofballs--Jeff, Brian, Mara, and Kelly--hear about a house that might be haunted, where someone disappeared years before, it sounds like the perfect case for them to solve on Halloween. But they'll need their best sleuthing skills and, of course, the help of the Goofdog, because this may be their silliest--and scariest--mystery yet.