The original idea I had for this story was a train carrying an Allied weapon towards Germany and the train to get accidentally rerouted into German territory.
But I think it is stronger to have the stakes be the loss of Allied civilian lives or the Allied POWs rather than simply the risk of getting captured.
Anyway, here is the logline for a WW2 thriller/drama:
Wrong Side of the Tracks
Escaped Allied POWs stow away on a train assembling a V-weapon, forcing a cool-headed captain and a working-class corporal into a collision over whether to escape—or sacrifice everything to destroy it before it reaches the launch site.
We’d start in the POW camp and see the working class corporal isolated and on the outer because of his background. He’s from the wrong side of the tracks. However, his background is the thing that gives him a knowledge of trains and makes him indispensable after the escape.