The planned marriage between Premierpiet and Probleempiet is in jeopardy, scholars Hans and Frans Steenstra have been kidnapped, and a rare ruby has been stolen from the Rijksmuseum. The dangerous Dr. Brein is behind all of this. Sinterklaas must intervene and even sends his Pieten on a trip to Switzerland to prevent Dr. Brein's criminal organization from gaining power.

When something bad happens at Aunt Til's exposition, the Sinterklaas fest seems to end once and for all. A series of terrible events is set in motion, which treatens to free the evil Dr. Brein and her accomplices.

When Sinterklaas and Diego arrive at the harbor in Spain, they discover that the pakjesboot has already departed. This marks the start of a race against the clock to catch up with the boat in time. That’s not easy, because thanks to the meddling of the crooks Joris and Boris, the Piets left for the Netherlands a day early...

The Piets are facing a modern problem. Most chimneys have disappeared, and many houses today are protected by alarm systems. The poor Piets are constantly chased by the police whenever they try to deliver presents to the children. One by one, they end up in jail. While Sinterklaas is busy trying to solve the Piets’ dilemma, he is kidnapped by the wicked Dr. Brein and her henchmen, Joris and Boris. Meanwhile, Pieta and Mrs. Dakjes are trying to teach a group of young Piets the skills they need for the job. They are also bothered by Michiel who wants to interview Sinterklaas for the school newspaper. Pakjesavond is approaching fast, and for both the Piets and Sinterklaas, it becomes a race against the clock to find a solution in time and save the holiday...

Sinterklaas wants to be absolutely sure that all the presents will be delivered on time. To make that happen, he has come up with a clever plan: a secret gift storage facility in the Netherlands! Months before the official arrival, he secretly goes to check how things are going. But when he arrives, he gets the shock of his life: there are no presents at all! The Piets have received false instructions, and the arrival ceremony has been mysteriously canceled. Someone is pretending to be Sinterklaas — but who…?

When Sinterklaas has an accident during the test for his “roof certificate,” he ends up in the hospital. Everyone is terribly worried — everyone except the evil Dr. Brein. She wants to use this opportunity to become Sinterklaas herself and change the holiday forever...