RAF sergeant John Dougall tells two French officers about how, with the help of agent Stefan Godowski, he escaped from a German POW camp and made his way to the French city of Reims.

It's a dangerous journey, fraught with obstacles: with the help of French Resistance fighters (one of whom he forms an all too brief romantic attachment to) he has to outwit spies for the pro-Nazi Vichy regime and German agents before arriving at the airfield, where he and Godowski roll a dice to decide who gets the only spare seat on the plane.

Dougall wins and flies to safety, and out of gratitude for Godowski's help he delivers some important papers to Godowski's Resistance colleagues. He finishes his account by citing it as a perfect example of how to execute such a mission.

However, one of the French officers is less than impressed by Dougall's account, and he tells the story again, adding crucial details omitted in the earlier telling.

In this version, Godowski is actually a Gestapo agent, and the Nazis allowed Dougall to escape because they thought it would be an ideal method of finding out the identities of key Resistance fighters.

After they'd given Dougall their assistance, Godowski lured them into fatal traps, and when they arrived at the airfield, Godowski deliberately rigged the dice throw so that Dougall would "win" and fly to freedom. Needless to say, the papers Dougall delivered on Godowski's behalf were actually Nazi communiqués designed to help the fight against the Resistance.

After hearing this version, Dougall is shocked to the core at the realisation that he has unwittingly betrayed his own side - and also that the woman he loved has been lured to her own death as a result of his carelessness.