In most cases where a musical is based on a novel, there are quite a few things in the book that are necessarily left out of the stage version, due to time constraints, to maintain a fluid narrative, or many other reasons. However, not with this book! I was amazed when I picked it up to see how short it was, and when I read it to see how closely it matched up with the stage version.
I had hoped to find within the novel a bit of clarification for some of the actions of the characters, but there really isn't any to be found. And the question many fans have about whether or not Alexis is really Jenny's father is left pretty much up in the air, except for this quote about Jenny as a baby: "When her eyes lost the opacity of a new-born baby's, there were seen to be neither green nor pure blue, but grey". As Alexis' eyes are also grey, this seems to be leading in that direction.
If you're a fan of the show, this book is a quick and interesting read, but if you're looking for something new, you won't find it here!
This book is out of print, and therefore not all that easy to come by, but you can try to get a copy at Amazon: