The political backdrop changed dramatically in January 1933 when the Nazis took power and converted Germany into a one-party dictatorship. Political activity (except in support of the Nazi party) became illegal. Arendsee was arrested in April 1933 and held in "protective custody" at the Women's Prison on Barnimstraße in Berlin in till September 1933. In April or May 1934 she emigrated via Prague and Paris to Moscow, where she joined her partner (described in some sources as her husband) who had already escaped from Germany to Paris in April 1933, in the aftermath of the Reichstag fire. In Moscow she undertook a succession of party and welfare related jobs, working at one stage in the socio-economic department of Profintern. She was also active in the leadership of "Foreign Workers' Clubs". From 1941 she also worked for Radio Moscow. For most of the time in Moscow she lived with . However, he was one of the many who fell foul of the dictator's paranoia, and he was arrested as a spy in 1937. He was released again on 13 January 1941, which according to one source was achieved through the efforts of his wife and friends. While Schwenk was locked away in the dungeons of the NKVD Ardensee's existence in Moscow was a relatively isolated one. 1941 was the year in which the non-aggression pact with Nazi Germany broke down when the German army invaded the Soviet Union. Between 1941 and 1943 Arendsee was evacuated to Engels, far to the southeast of Moscow. In 1943 she was one of the co-founders - according to one source the only female among them - of the Soviet sponsored &lt;a href="National%20Committee%20for%20a%20Free%20Germany"&gt;National Committee for a Free Germany ("Nationalkomitee Freies Deutschland" / NKVD)&lt;/a&gt;, an organisation for which she worked till 1945.