In Vienna, a streak of murders envelop, committed by an unknown killer. Julie Wardh, a mentally fragile American socialite and heiress to the Wardh's retailing fortune, is targeted by this unknown assassin through letters of blackmail. Julie suspects her ex-lover Jean to be the man behind the letters but does not wish to confide in her husband Neil. Instead Julie falls for, and confides in, a cavalier by the name of George whom she takes as her new lover. As events unfold Julie is reminded of her past sadomasochistic love affair with Jean all the while suspicions are raised against both George and Neil as the possible culprits. Who is the killer and what does he want from Julie?