Adil Bahdari goes to Passau when he hears that a fisherman has found an expensive watch on the banks of the Danube with an inscription on the back. The watch was a gift from Adil Bahdari to his son Ahmed, from whom he has not heard for some time. He hires private detective Ferdinand Zankl to find his son. But it is Zankl who is behind his son's death.—Jakkepoes