Reiff für die Insel - Katharina und der große Schatz.

At the end of winter, there is a game of bowls in the north. The islanders are proud of their bowling ball, which Thies' grandfather found 60 years ago. Only Katharina believes the archaeologist Jens Jeschen, who wants to examine the sphere in a laboratory on the mainland and suspects a Viking grave and treasure on the island, that it is a medieval celestial globe.