Inside the Illusion — K.A. Applegate

There is a place that shouldn't exist -- but does. There are creatures that shouldn't exist -- but do. Welcome to a land where all of your dreams and nightmares are very real -- and often deadly. Welcome to Everworld.

Senna. She is the reason David, Christopher, April, and Jalil even know about Everworld: She is the one who they've been chasing all over this strange parallel world to get sonic answers„ To show them how to get home again. To get back to the real world.

So now its her turn to tell her side of the story. To explain why she dragged her friends into a world of winged horses and wizards. A place that once only existed in their imaginations. Now it's her turn to explain Everworld..