On the night of 7 October 1943 Käthe Niederkirchner celebrated her 24th birthday by jumping out of a Soviet military airplane in the countryside near Warsaw. She was accompanied in the enterprise by a fellow activist called , who was also the son in law of Wilhelm Pieck, a leader of the group of exiled German communists based in Moscow at this time. Her parachute caught in a tree from which she was rescued by Polish partisans. The whole of western Poland was still under German occupation. The Polish partisans also helped Niederkirchner and her companion make their way to the nearest railway station. (The leader of the group involved later became a Polish ambassador to the German Democratic Republic.) Niederkirchner's instructions were that she should make her way to Berlin, but she and Winter were caught and arrested in or near Königsberg before she ever reaching their destination. It later transpired that they had been betrayed to the German authorities by someone on the Russian side. In Niederkirchner's rucksack the police found a radio transmitter. It had been the intention of her Soviet handlers that she should use it, in working with "resistance groups" believed to be active in Berlin, to help facilitate and hasten the invasion of Berlin by the Red army.