The Underneath by Kathi Appelt

The Underneath is the weaving of two stories into one.  One story involves three calico cats, a hateful man named Gar Face and an old hound dog.  After the mama calico cat gives birth to twin kittens, they befriend the old hound dog who is living underneath the run-down house of his owner, Gar Face.  There is one important rule that has been preached to the kittens their entire life and that is not to go into the Open, you will be safe in the Underneath.  The lives of these three lovable characters are going pretty smoothly until one of the kittens, Puck, forgets himself for a moment and breaks the rule.  The other story contains magical creatures such as Grandma Moccasin and Hawk Man.  Grandma Moccasin has been trapped underground inside a jar for a thousand years after losing her beloved daughter.  Through the story, we learn what happened so many years ago that put her into the jar.   The events of a thunderstorm finally  break her free and she becomes a crucial part of a climatic event.  Even though at first the two stories do not seem connected at all, they become woven together towards the end of the book.   Although heartbreak is a part of this story, so is love and the powerful impact it has on our lives.