Everyone's favorite preteen British detectives are back for another case! With toddlers disappearing and rumors of a large, beast-like creature roaming the woods, Tackleford is in serious danger. And then there's Mildred's new dog Archibald... if you can even call it a dog. After all, what kind of dog drinks tea out of a cup? Everything comes to a head once the boys get a picture of the beast and Archibald goes missing. Is there a connection? And what does it all have to do with the magic pencil Mildred won from a carnie con game?