The plot thickens! There is a major connection between the dragon, the rat creatures, and Bone's new family, Thorn and Grandma Ben. I don't want to give anything away, but I will let you know that the story is getting pretty interesting. I foresee lots of adventure in later books!
Be sure to read the books in the "Bone" series in order. They are telling an epic story that is only now starting to reveal itself. If you liked the first two books enough to stay through to this one, you will not be disappointed!