I would say a big part of this book is about the food chain. the little brother gets swallowed by a creature, and the big sister embrakes on a journey to save him. and each and every time she almost makes it another creature comes and eats the previous one. but she does eventually makes it, and save her brother using a toad, yep, a T-O-A-D. (I suspect you can only find these kind of solutions in children books). but then all the creatures wants to eat the sister, so the brother steps up and says that if the dare he would eat them all. and guess what? the creatures are scared of him, of the little boy one of them swallowed before! that was hilarious. I think children would really love this book.