On Christmas Eve 1942, Lothar Orbach, a Jewish teenager, was with his mother in their one-room Berlin apartment when the doorbell sounded. They knew immediately it was the Gestapo, come to take them away. They managed to slip out in order to escape via the tenement’s rear door, which the superintendent had agreed to keep open for just such an occasion. It was locked. They knocked on the door of an old man who had known Lothar since he was small. He slammed the door in their face, then turned up the record player. It was playing Handel’s Messiah.Other neighbours...