Das letzte U-Boot

A mission about to begin, a war about to end. The year 1945, few days before the german rendition to the allied forces. A german submarine with some japanese crew is sent to Japan to deliver a plutonium cargo. This radioactive element would help the japs to develop the atomic bomb before the americans. But before the U-boat reach the first half of its itinerary, a transmission announcing Hitler's suicide and the german rendition to the allied forces is received. So the war is over, but only among the allies and Germany, what about Japan? So, the capitain has to choose between complete his mission or surrender to the first american force they find.