Tristan und Isolde centres around two lovers who dream of romantic love and yearn for oblivion. No composer had written such a work before. Turning his back on traditional tonality, Wagner changed the course of Western music with Tristan und Isolde. But there's also fact behind the fiction: while he wrote his opera Wagner was in love with another's man's wife, Mathilde Wesendonk. So Tristan and Isolde are also Richard and Mathilde. Christopher Cook explores the making of a masterpiece, the story of lovers gripped by a passion that can only be consummated beyond the grave, a forbidden love that is blind to duty, honour and social obligation.