Poles under the command of Johann and Anna are preparing to attack the battleship Bismarck. They want to place mines along its route. During the preparations, they are surprised by the Germans led by Kessler. Anna wants to kill them by blowing up mines. During the action, he notices that Franz is also among the Germans. She suspects him of betrayal. Johann soon explains to her that the mine operation was just a smokescreen intended to make Franz credible to the Germans and distract Kessler. At this time, divers led by Franz into the port planted explosives in the basin where Bismarck was moored. However, Anna still does not trust Franz and follows him.