Berlin express (1948)

It's the postwar period and tensions between nationalities from the war still exist. A Berlin via Frankfurt train operated by the US Army has just departed Paris, it one specifically dedicated to people traveling for official duties and their companions, duties including diplomatic, governmental, military and the like. Frankfurt is the headquarters of the American zone, Germany, post-war, divided into four zones, one controlled by each of the primary Allied forces of the Americans, British, French and Soviets, each nationality plus some Germans among the passengers on the train. Arguably the most important passenger is German Dr. Heinrich Bernhardt, an international affairs specialist and head of a fact finding mission, his report recommending how to bring the four zones back together under a united and peaceful Germany facilitated by those in control. He is heading to Berlin to report his findings to those in power officially and publicly. When it looks as though Dr. Bernhardt's life may be in jeopardy seemingly at the hands of German nationalists who do not want him to make his report, they instead wanting Germany's fate controlled solely by Germans, a small group of disparate passengers comprised of all five of the nationalities take it upon themselves, centered on who reveals him/herself to be Bernhardt's secretary, to protect the Doctor for him to be able to make his report in Berlin as scheduled, they needing to be wary of possible moles and other imposters in their midst.