Erik Lund is a professor in child psychology. When his sister and her husband go on vacation, he is left in charge of their five children. He really feels up to it, since he is now going to be able to try out his skills in child psychology. However, reality is something else than theory and children do not always do as they are supposed to, according to his book on child psychology. The children soon fool him into doing as they please when it comes to food and pleasures. However, soon they start to realise that if they can make him serve them hot dogs and hamburgers and let them watch TV as much as they like, they can also make him help them restore their old house, so that they won't have to move, as their parents want to. And, as their uncle is nice enough to help them, they also decide to try and get him a wife.

The whole family is going on a skiing holiday in Norway when Dad breaks his leg. So Uncle Erik takes the five oldest children. On the ferry, Amalie meets ski instructor Dan, and Uncle Erik gets very seasick. It turns out that Dad has rented a very small, leaky cabin, but Jan and Michael sort it out so they can move into a large suite. It turns out that it has been rented to Mrs. Flinth and her friends, and she causes a lot of trouble. The family is thrown out, but once again Jan and Michael fix the situation. They claim that Erik Lund is a famous singer. Erik is busy looking after Amalie, but when she discovers Dan's flirting with another girl, she gets the boys to help her. Meanwhile, Erik also finds time to go ice skating with Mrs. Flint.

Five young siblings deal with a reluctant chaperone when they wind up stranded on a trip to Egypt.

My sister's kids this time are going to Jutland.

This time, the children's parents have gone on vacation to New York, and it is up to Uncle Erik to take responsibility for his nephews and nieces, or at least try to. Everything seems to be going well, until Jan and Michael take a little drive in their father's new sports car. The mechanic's bill comes to $30,000, so the children persuade their uncle to open a hotel in their own house. The hotel quickly fills up, but not all of the guests are easy to please. And the strict Mrs. Flinth is definitely not happy with the children's successful hotel business!

This time our already familiar family moves to Africa in order to save endangered wildlife.

Family film 'My Sisters Kids & the Gold Diggers' sends Uncle Erik and the kids on a new adventure. This time discovering the children that their great-grandfather emigrated from Denmark and was a gold digger in Canada. Even now, many years later, they still have family over there. So when the family comes in contact with an aunt, they travel across the Atlantic to visit her. In Canada awaits them a true treasure hunt, the wild and two greedy prospectors. At the same time they are joined by Mrs. Flinth which, as always, has a crush on Uncle Erik.