When twelve-year-old Adeline Perle's transient military family finally plants roots in an old, creaky mansion - Cannondale - the girl craves to build the lasting friendships that she, as a constant outsider, never had. At last, on the cusp of bonding with a new group of affable teens on Cannondale's grounds, Adeline discovers an unusual treasure behind a secret door, unveiling portals to extraordinary realms where she is confronted with disappearing creatures and magical people, good and evil, and a boy who's desperate to help her find her way back home.

But not all friends are as they seem. Some will go to any length to get what they want, including a secret Adeline does not even know she possesses. It is a secret so important, all the magic in the universe is at stake. Wars have been waged over it, and Adeline finds herself right in the middle of it all. She must overcome all inhibitions and face her greatest fears not only to survive but - after a lifetime of wanting - to find her place and way home.