When Germany invaded Holland in May 1940, Sabine Zuur joined the resistance movement without a moment's hesitation aged just 22. Helping to hide those avoiding the German authorities, she was soon betrayed and subjected to repeated violent interrogations. Many of her friends were executed but Sabine was instead sent to the Mauthausen concentration camp, via the Amersfoort and Ravensbrück camps. Enduring gruelling conditions and backbreaking forced manual labour, she survived through a combination of guile and good fortune. But it was only after Sabine's death that her daughter Eva discovered an archive of letters detailing her extraordinary life, revealing a rich inner world and a past she had discussed little.