The Unwanteds #5 Island of Shipwrecks by Lisa McMann

My twelve year old is reading this series to himself and wakes up early (and stays up late) to read the books!  He is enjoying them!
Alex and his friends are trying to return to Artime, but are shipwrecked on an island.  The island contains clues to its past.  Alex and his friends may not be as alone as they think are!
Alex's twin, Aaron, continues to raise support for himself and his army, desiring to conquer Artime.
-Borrowed from the library.