On New Year eve in Paris detective from Bern Wachmeister Studer and his friends from French Criminal Police made an acquaintance with priest who was on his way from Morocco to Switzerland. The priest told them the story about clairvoyant corporal from Foreign Legion in Morocco who predicted death for his two sisters-in-law; one lived in Basel and another in Bern. The policemen didn't take the story seriously, however when Wachmeister Studer arrived the next morning to Switzerland he learned that both women died after gas poisoning at similar and very suspicious circumstances. Wachmeister Studer was convinced that he dealt with double murder and started the case investigation which led him from Bern to small Foreign Legion garrison Gurama in Morocco. During the investigation he became involved in the intrigue in which families and political interests were closely intertwined.