Unlike many another pre-WW II spy melodramas, clearly identifies the villains as Germans. Joel McCrea plays Barry Corvall, the son of a recently deceased US diplomat. Boarding a Berlin-bound train, Corvall attempts to swipe a briefcase stuffed with documents which will prove that the Nazis have been infiltrating vital industrial centers in the United States. He is helped along by Brenda Ballard (Brenda Marshall), whose behavior suggests at times that she might not be all that trustworthy. According to the Warner Bros. publicity machine, Warren Duff's screenplay was based on actual events. Coming on the heels of the studio's , was indication enough that Warners had declared war on Germany long before President Roosevelt made it official.