It's 1943, and the Germans are in control of the French port of Marseilles. Although the Nazis seem to be having plenty of fun at the local bordellos, they're upset by the amount of crime in the poor part of town, and suspicious that anti-Nazi plots are hatching there. Dave (Stephen Boyd) and Jim (Tony Wright) are English POW's who have recently escaped from Germany. They are hiding in a tiny apartment waiting for the French resistance to arrange their passage to England. Bored with captivity the Englishmen venture out and Dave falls for local woman Lise (Anna Gaylor). Meanwhile the mysterious Dr. Martout (James Robertson Justice) makes a living by helping escapees on their passage out of the city, but all is not what it seems! Given an ultimatum to quell the French Resistance, the German Commander decides to demolish the crime-infested Old Quarter, where Dave and Jim are hiding. Dave wants to wait for the resistance, Jim chooses Dr. Martout, but will either of them see England again?