Plan B was to poison German soldiers at an American-run prison camp. The Holocaust survivors had members of their group working in the bakery that supplied bread to the camp, so they would be able to lace the loaves before being delivered to the camp. Initially they ran into the problem of how to make sure that only the Germans and not the Americans would be killed, but then it was discovered that the prisoners ate dark bread while the guards preferred white.
Based on a true story.