Vienna, 1904.
The body of a man is discovered in an abandoned piano factory on the outskirts of the city. Detective Inspector Oskar Rheinhardt calls on his good friend Doctor Max Lieberman to assist in an investigation that draws them both into the unconventional world of fringe political activism. An appalling act of terror has been planned, and Rheinhardt must hope that Liebermann, with his profound knowledge of psychology and science, will be able to prevent the coming catastrophe.