On a trip from France to Allied-occupied Berlin, a group of travelers — a mysterious and very secretive European woman, an American agricultural expert, a British educator, a Soviet Army officer, and a French official — all cross paths in the cramped quarters of a military train. They discover that the notion of the "Allied forces" is breaking down amid their victory in the war; they neither like nor trust each other, nor each other's countries, except where the Germans are concerned, where they share a distrust. And then they cross paths with a German VIP who makes them wonder if they've got all of the Germans pegged right. A bomb goes off, killing their newfound acquaintance, and the suspicions start anew. The mystery surrounding the victim only deepens when they discover that he wasn't who he claimed to be — and that the army isn't saying who he was. They soon find themselves up to their necks in unrepentant Nazis and militant German nationalists who have banded together against the occupiers to destroy any chance of success for a peace plan being put forward by a visionary German. They find Frankfurt a hotbed of sabotage and armed underground resistance, with the occupying armies seemingly caught flat-footed by the plotting in their midst, which includes murder and blackmail.