During the occupation of World War II, the owner of a Dutch shipping port is ordered to attend an interview with the head of the Gestapo.
His yard has almost completed two submarines and the Nazis are anxious to have them finished and fully operational. They offer to reinstate him if he agrees, which he does.
But what the Nazis do not know is that he is planning to double cross them and take the ships to England, if he can. Starring Ralph Richardson, Googie Withers and Esmond Knight.