The synopsis in the CD booklet doesn't really tell you the whole story. It focuses on 4 of the characters. I am assuming the high pitched voice is Gideon Glick. If you listen to the song, you should be able to realize what's happening. The songs don't really "tell" the story. They are mostly about what is going on in their minds during certain scenes. Although you can pick up what's going on for the most part.
There is a synopsis of the story on the show's website.