Davina Dupree and her best friend Arabella enjoy their day out down an old smuggling tunnel that leads from their boarding school's cellars to a nearby beach. But after returning to the school that evening they discover a crisis has occurred - someone has stolen all of Marcel the chef's expensive ingredients! This means that Arabella may never be able to eat her favourite pudding, Magic Mousse, ever again! Davina and Arabella resolve to solve the mystery, a decision that plunges them into a murky world of smuggling and intrigue. The question is, will they be able to rescue the ingredients in time or will the smuggler get the better of them?