[1] Through her younger brother, Tim (1923-2013), she met Luftwaffe Sergeant Helmut Schmidt, the future Chancellor of Germany, who, from 1937, was stationed in Bremen-Vegesack for his military service and during this time had an intense friendship with the Bontjes van Beek family.

However, Schmidt eventually broke off this friendship when he began an officers' training in order to join the Oberkommando der Luftwaffe in Berlin.

[citation needed] Beginning in 1940, Cato and her younger sister, Mietje, lived with their father in Berlin, where he had already moved in 1933 in the hopes of spreading his artistic work.

[1][3] Van Beek's active work against the Nazis began in the Red Orchestra resistance organization after she had gotten to know Libertas Schulze-Boysen in autumn 1941.

[1] Together with her friend, the author Heinz Strelow, she distributed illegal writings and leaflets which sought to arouse readers to the struggle and resistance against the Nazi regime.

[4][5] In the course of the suppression of the resistance group, van Beek was arrested by Gestapo agents on 20 September 1942 in her father's pottery shop in Berlin.