Can you whistle, Johanna?

Young Berra has a friend, Ulf. Ulf has a grandfather which he likes very much, he gives Ulf presents and takes him on fishing trips. Berra doesn't have a grandfather, but he wants one that's nice to him and who can teach him to whistle. Ulf knows where to find a grandfather - at a home for senior citizens. They go searching together and Berra finds a great pretend grandfather, Nils.