1899. The Golden Vienna is experiencing an unprecedented flowering of fine arts. Fans and music connoisseurs from all over Europe come to the Vienna Opera. But unexpectedly, on the stage of the best stage in the world, a completely non-theatrical bloody drama is being played out... Someone is trying to kill the great composer Gustav Mahler. Worse, Mahler may not be the first genius to be targeted by an unknown killer. The police are powerless. And then Mahler’s fiancée, the social beauty Alma Schindler, asks for help from the best detectives in Vienna - the brilliant lawyer Karl Werthen and his friend, the brilliant criminologist Hans Gross - great lovers of sophisticated and dangerous mysteries...