Coded clues, midnight escapades, secret societies . . . These and more await Rollie Wilson as he enjoys his Christmas vacation from Sherlock Academy of Fine Sleuths. While Rollie’s school is on break, the mysteries surrounding the elusive Herr Zilch continue. Rollie, Cecily, and their detective comrades discover a prowler has sneaked into Zilch’s empty mansion that is filled with secrets of Zilch’s evil schemes. As the mysteries and dangers increase, Rollie and his friends’ safety is threatened. Will Herr Zilch come after the young sleuths? Will Rollie uncover the secrets within the mansion? Can Rollie and his comrades stop Zilch before he destroys the Academy?