It is 1942. In Nazi occupied Poland a prostitute is murdered in her apartment and Maj. Grau, German Army Intelligence, is called in to investigate the crime. The only clue is that the murderer wore grey pants with a red stripe. He realizes that only high ranking German generals wear grey pants with a red stripe. Before he can complete his investigation Maj. Grau is promoted to Colonel and posted to Paris.
Two years later, in Paris, another prostitute is murdered. There are similarities in the crime to the one in 1942 and Maj. Grau again takes charge of the investigation. The three main suspects from the previous investigation, coincidentally, all happen to be present in the city at the time of the murder. He puts the clues together and is about to aprehend the killer but in the confusion of the allied advance, and other circumstances involving the German military, he is killed before the investigation is completed. The war ends, years pass.
It is 1965. Fragments of the Nazi party still hang on. In Germany a third prostitute is murdered, again, in similar circumstances. A Parisian detective, involved in the second investigation in 1944 and now a member of Interpol, who investigates realizes that the murderer is the same man who committed the two previous murders years earlier. He revisits the surviving witnesses from Maj. Grau's original investigations and finally confronts the killer at a reunion banquet held in the killer's honour.
When Maj Grau is promoted to Colonel, to what city is he assigned?
Paris