The Allied Forces are days away from liberating France, but that gives one enterprising Nazi officer a chase to abscond with a priceless collection of French art. He has to rely on the French locomotive engineers to get it out for him, some of whom work for the Resistance and the others like-minded. Thus begins a fiendishly clever and complicated battle of wits. Intriguingly, sometimes the two sides find themselves with common interests: neither wants it destroyed in an air raid, or by an act of sabotage.

In the course of the film, this train will be put through just about everything a train can be put through, and the characters don't fare much better. Director John Frankenheimer captures some spectacular visuals by not using special effects: when two locomotive engines crash into each other, it looks real because it is.