Fraternal twins Lenny and Cassy of modern Seattle live alternative lives in the parallel world of the Kingdom of Duscany. He is known as Prince and Master Sorcerer Leonard and she as Cassandra, the Queen of the Whelfs.
 
While recuperating from their battle with an evil whelf called Night Shadow they visit Princess Jenna’s Uncle Scapita in Kings Keep, but he has an unusual visitor named Kamp, the Blaine of Stroop Town who offers a thousand pieces of gold for his help in locating Leanne Mellot, his betrothed, who vanished ten years before. Scapita shrugs off the chore onto his niece Jenna and her friends, Lenny and Cassy, who accept the offer.

They soon find that the mystery goes deeper than the ten years she’s been missing, even deeper than the thousand years it’s been since the old Kingdom of Eskeling was destroyed by the man-thrall. The plot goes back to the Master Sorcerer Mercilus himself.

The trio of children must discover the reason why four rampaging monsters have appeared in the Whelf Fen or suffer the destruction of the Kingdom of Duscany along with their friends.