When they are still little girls, Cibi, Magda and Livia make the promise to their father that they will always stay together. When Cibi and Livia are ordered to Auschwitz-Birkenau labour camp by the Nazis, Magda manages to hide out for a time in a neighbour's attic near her family home.Eventually the sisters are reunited in Auschwitz where they renew that promise, this time to each other. Together they manage to survive the death camp and forge a new life for themselves.In this episode Gregory Dobbs chats to Heather Morris about the fortuitous moment that was the catalyst for Three Sisters, the power of familial bonds and turning real people into great characters to bring history to life.