Two weeks have passed since the Green Beans solved the mystery of Hollow Oak, making remarkable discoveries in the process. In the wake of their findings, Jack has been placed within the huge, eerie manor of his new guardian an eccentric uncle, known as Lefty O'Houlihan.
Before long, Jack comes to suspect that something strange is afoot in his new home. Weird noises, curious sights, and his uncle's odd behavior have led Jack to believe that all is not well at Lefty's Manor.
Seeking help, Jack finds that his friends are more than ready for adventure and investigation. Neil, Sara, and Maria gladly answer the call, along with Nibbler, the faithful Labradoodle.
From the rumors that the Green Beans have been able to gather, it seems that Lefty may have once been a brilliant scientist until his 'strange genius' spiraled out of control, forcing him to part ways with his former employers. Now, the Green Beans are determined to uncover the truth behind Lefty's current scientific project and what it may mean for the future of Hollow Oak.