Anita Lasker survived the Holocaust because, as a Berlin teenager, she had enjoyed her cello lessons. The Hungarian Lily Mathé’s violin performances had once impressed the man who became the Auschwitz concentration camp commandant. Alma Rosé, among Europe’s most talented musicians and the niece of Gustav Mahler, became the conductor who kept these young women and more than 40 others alive through ‘ferocious discipline’ and determination.