Sarah Montague speaks to Yazidi rights activist Nadia Murad. When militants from so-called Islamic State entered Nadia's village, they killed all the men; six of her brothers were murdered. She and hundreds of other Yazidi women were taken captive and, in the months that followed, they were passed from one group of men to another and gang raped. She managed to escape, but it is thought that thousands of women are still being held captive. Nadia Murad is here in London campaigning to try to get the world to notice and do something.