"Götterdämmerung" ('Twilight of the Gods') is the final opera of Wagner's epic tetralogy "Der Ring des Nibelungen" ('The Ring of the Nibelung') in which his visionary masterpiece reaches its cataclysmic conclusion. Betrayal and death, murder and remorse, lie at the opera's heart, in a work that draws together every plot element in writing of blazing intensity. As the Ring...