It's November, and there's a new mystery to solve. 'The twins' new neighbors are up to something! It's Thanksgiving, and a mysterious couple has moved in next door. Bradley, Brian, Nate, and Lucy mustwork out the clues: The neighbors have built a tall wooden fence. They've bought some strange parts formaking . . . something. They've even put up a suspicious tent in their backyard, with a big, scary dog to guard it. What could they possibly be hiding?