Download or read book The Riddle of Zorfendorf Castle (The Secrets of Droon #25) written by Tony Abbott and published by Scholastic Inc.. This book was released on 2016-02-23 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: A hidden door. A magical staircase. Discover the world of Droon! There's only one passage between the Upper World and Droon -- the magical rainbow staircase. At least, that's what Eric and his friends have always believed. But now Ko and his beasts are attacking Zorfendorf Castle, a magical fortress that's hiding a huge secret: the Fifth River, another passage to the Upper World. Ko will do anything to get to the river -- and to the Upper World. And Eric, Julie, Neal, and Keeah will do anything to stop him!