High Tide in Hawaii

One summer day in Frog Creek, Pennslyvania, a mysterious tree house appeared in the woods. Eight year old Jack and seven year old sister, Annie, climbed into the tree house. They found out that it was filled with books. Jack and Annie soon discovered that the tree house was magic. It could take them to the places in the books. All they had to do was to point to the picture and wish to go there. While they are gone, no time passes in Frog Creek.Along the way, Jack and Annie dicovered that the tree house belongs to Morgan le Fay. Morgan is a magical librarian of Camelot, the kingdom of King Arthur. She travels through time and space, gathering books. Jack and Annie have many exciting adventures helping Morgan and exloring different times and places.

this is from a 9 year old so watch out.