In the concentration camp of Auschwitz, Dr Josef Mengele performed experiments on more than 3,000 twin children. Only 200 survived. Tonight's Everyman focuses on the lives of five of them. Peter Greenfeld still has nightmares every time he visits a hospital. He is convinced that his twin sister Miriam survived, and he has spent the past 25 years searching for her. Other survivors, like Vera Kriegal , have broken all contact with their twin because of memories too painful to bear.