A sexual predator is at large on the streets of Imperial Vienna and Detective Inspector Oskar Rheinhardt appeals to his friend, psychoanalyst Dr. Max Liebermann, for assistance. Early signs indicate that the killer is no ordinary 'lust murderer' but an entirely new phenomenon, his particular deviance revealing the darker preoccupations of the age. To understand his behaviour, Liebermann must employ the latest developments in psychoanalysis and make a journey into uncharted regions of the human mind. Alongside the unfolding of this disturbing case, Liebermann must treat his own patients, including a man who claims to have seen his double - the doppelganger of Germanic folklore - an experience believed to be an omen of death. As Liebermann discovers more about this seemingly harmless man, he becomes convinced that his hallucinations are caused by a traumatic memory, buried deep in his unconscious. Could a mysterious dream hold the key? As the investigations proceed, Liebermann and Rheinhardt find themselves drawn into the worlds of art and couture, worlds in which glamorous appearances mask the most sinister secrets.