During the annual family weekend in theme park "De Efteling", eleven-year-old Teun discovers that his recently deceased grandfather left him one last scavenger hunt inside the park. Although most adults think this is nonsense, Teun embarks on an exciting expedition through the theme park with his quirky aunt Ada to find out exactly what his grandfather has hidden for him. Soon Teun finds out that it concerns grandfather's very precious fairytale book. But Teun and Ada are not the only ones who are after the book; a mysterious figure is constantly a few steps behind them. Will they manage to find the book in time and thus keep the Vos family together?