This film is not only a revealing glimpse into the workings of the O.S.S. (Office of Strategic Services) during WW II, but it is also a full-fledged spy thriller. An excellent cast includes James Cagney, Karl Malden, E.G. Marshall, and Red Buttons. Cagney stars as an O.S.S. training officer, bent upon discovering a German traitor within his ranks while at the same time completing highly dangerous espionage assignments. The risks increase when one of his men is murdered from within, and Cagney, convinced he knows who the murdering infiltrator is, vows revenge. Authentic O.S.S. film footage make this film historically significant as well as entertaining.