Fisherman's son Benjamin 'Bennie' Stout is mischievous, in a prank war with the mayor's spoiled-rotten son Roderik, and accident-prone, making life hard for his big brother Steven, who left school to help pay the bills, and their mother Rietje. When they hear that father Willim isn't returning in December to earn extra cash in Bilbao, Bennie decides to join him in Spain. As he can't afford passage, he devises to be naughty enough--which comes naturally--to be snatched into St. Nicholas's helpers' bag with the other worst kids as every year, even writing his own name in the book instead of Roderik. However St. Nick usually lets kids escape or returns them and isn't convinced Bennie is truly naughty rather then missing his father's firm guidance, so Bennie keeps trying to prove himself worse than ever. Still, everyone is in for more surprises.