In 1929/30 she undertook a training in the book trade, after which, still aged only eighteen, she moved to Berlin where, between 1930 and 1934, she was employed by the Marx-Engels publishing house. The period was one of growing political awareness: in 1931 Brunhilde Rothstein joined the Communist Party. In January 1933 the Nazi party took power and lost no time in transforming Germany into a one-party dictatorship. The Reichstag fire at the end of February 1933 was immediately blamed on "communists", and it was individuals and institutions connected with the (now illegal) Communist Party that found themselves at the top of the government target list. The Marx-Engels publishing house, where Rothstein worked, was owned by the Moscow based Marxism-Leninism Institute and the Nazis closed it down. Acting on instructions from the institute back in Moscow she now went each day to the in central Berlin where she borrowed, and the copied out any articles she could find on or by Karl Marx, then delivering the copies to the . This activity ceased after the library director banned her because, as he put it, he did not want a nice German girl corrupted with Marxist literature. It was as she recalled the incident many years later that she wryly added that, with her blonde hair and blue eyes, it would never have occurred to anyone that she might be Jewish.