Peter Keller, who lives in Berlin, receives a letter from his homeland, the Swiss Emmental. Otto Balsiger, who had served in the army as a soldier under Keller's command, is accused of raping and murdering a woman and asks Keller for help. Keller, who firmly believes in Balsiger's innocence, tries to find out the true background to the crime on his own. However, his investigations quickly make him unpopular with the villagers, and it seems he can't trust anyone. Only Josef, an old friend of Keller's who has since become the leader of a religious sect, and Uta, the mayor's daughter, seem to be honest and friendly to him.