An urgent telephone report of a crime at Tigergasse 16 draws American detective Joe Jenkins into an investigation within Weimar-era Berlin. The inquiry leads Jenkins to the "Club of Doubters," a group dedicated to spiritualist practices and the pursuit of messages from the deceased. During a séance intended to manifest the spirit of an executed man, the proceedings are interrupted by a fatal shooting.
Because the room was secured from the inside and the incident occurred in total darkness, Jenkins determines that the perpetrator must be one of the attendees. Paul Rosenhayn, utilizing his background in silent film structure, crafts a narrative that explores the tension between rationalism and the occult. The story functions as a classic locked-room mystery, where the detective must navigate the deceptive atmosphere of the séance to identify a human killer among those seeking the supernatural.