Nothing is more inviting to disclose your secrets than to be told by others of their own ...

London, June 1965. Karl Braun arrives as a lodger in Pimlico: hatless, with a bow-tie, greying hair, slight in build. His new neighbours are intrigued by this cultured German gentleman who works as a piano tuner; many are fellow emigres, who assume that he, like them, came to England to flee Hitler. That summer, Braun courts a woman, attends classical concerts, buys bacon, dances the twist. But as the newspapers fill with reports of the hunt for Nazi war criminals, his nightmares become increasingly worse.