Mould and Jessica become friends. But Jessica, with the unwitting assistance of Mould, manages to escape back home. Now Fungus and Mildew must create a plan of damage limitation. They determine that Fungus and Mould shall go back above ground to find Jessica, make sure she hasn't told anyone and if she has, either bring her back, or block up the Bogeyhole. Meanwhile, an exhausted Jessica has told her parents about her adventures, and her father George, sees this as his chance to advance his stagnating newspaper career to get the big story. He is determined to catch a Bogeyman...