When Sinterklaas has an accident during his exam for his 'roof certificate', he has to go to the hospital. Everyone feels terrible, except for the evil Dr. Brein. She wants to use this opportunity to become Sinterklaas herself and change the holiday forever. Dr. Brein tries to steal the money for the presents with her henchmen Joris and Boris and make off with the Big Book of Sinterklaas. When Agent de Bok loses his job, he sets out to investigate with the Pieten. Will they succeed in bringing this exciting adventure to a successful conclusion and securing the Big Book of Sinterklaas before December 5?