Story : May 8, 1931. The special U.S. mail train, coming from Rock Island, is stopped by emergency flares on the tracks in Hillsdale, Illinois. Gangsters wearing Army gas masks lob tear gas grenades into the train; they shoot a postal clerk and make off with a million dollars in negotiable securities. 3 months later, ""Tough"" Tommy Karpeles, former big-time Chicago hoodlum, is arrested for complicity in the case; his 2 accomplices were not caught.