Adapted from a novel by Philip Gibbs, a war prisoner learns that his wife loves another prisoner, who escapes but is returned for a trial.
In a German prison camp Haversham grabs a gun and shoots himself; but another prisoner takes the gun and shoots German guards. Many prisoners are killed, and the men are shut up in a cellar. Captain Fred Allison (Leslie Howard) reads a letter from his wife Monica (Margaret Lindsay) and recalls saying good-bye to her after only six days together. She wrote that she went to the theater with Digby, who is missing. Men want to break out; but Commandant Ehrlick (Paul Lukas) orders Allison to keep the men quieter. Allison asks for huts and promises that the men will behave. Ehrlick agrees and says that he was at Oxford too. Allison sees Digby (Douglas Fairbanks Jr.) with the new prisoners, gets in the same quarters, and asks him about Monica. Allison tells Digby that he gave his word to Ehrlick. Digby gets a letter from Monica that she loves him and not Allison, who is desperate to hear from her. Digby says he has to go and tells Allison to turn him in.
At night Digby cuts the barbed wire while a German woman is raped and murdered. Digby hits a German and takes off in a plane. Ehrlick asks Allison where Digby is. Digby's German plane is shot down by the English, but he makes it to the English lines. Ehrlick asks Allison to sign the letter summoning Digby to a trial, or all prisoners will be punished. Allison reads the letter from Monica and signs. Digby goes to London, and the British get a letter accusing him of rape and murder. Digby kisses Monica and tells her that Allison loves her. Then Digby is arrested, taken to the Provost Marshall, and is sent back to France. Digby says he is innocent but is returned under a white flag.
At the trial Digby says no more than that he is innocent, but he blames Allison for bringing him back. Digby is found guilty and is sentenced to be shot. Allison tells Digby he was wrong, and Digby says that Monica never loved Allison, that she was frightened and lonely; Digby waited to see if she loved him. Allison finds a note from Strogin (John Bleifer) saying he did it. Strogin is found hanged. Allison sees the firing squad and stops it, showing Ehrlick the note. Allison plans an escape at six and asks Digby to tell Monica the marriage was a mistake. Allison takes a gun from a guard and shoots. The prisoners rush the gate as Allison uses a machine gun. Men fight Germans for the planes. Digby and others take off in planes. Allison is killed by a grenade. Digby and Ehrlick each salute the dead Allison.
This drama shows how war can cause a quick marriage and a painful separation for the prisoner. Yet both sides still recognize some law even as they are working as hard as they can to destroy each other.