Pursuing an escaped fascist agent, Soviet criminologists N, Kruchinin and his friend find themselves in a small town in northern Europe. At the hotel, they meet the skipper of the schooner Anna, Hjalmar Heckert, his brother Vidkun (a pawnshop cashier) and the local pastor. The next day, the skipper is found murdered in his cabin. Suspicion falls on Knud Ansen, who served as a guide for Kruchinin and his friend.