Artist André Fortis is the victim of a strange curse that suddenly and unexpectedly turns him into an entirely different man, with his own life, artistic styles and preoccupations, thus splitting his existence into two separate lives -- his and the Other's. Can he be cured by the mysterious Dr. Klipper who claims to have invented devices that can read the human brain through the skull like an open book? Jules Clarétie's Obsession (1908) deals with the psychological anomaly that would nowadays be called multiple personality syndrome in the tradition of the classic Strange Case of Dr Jekyll and Mr Hyde (1886). Although it remains an "evil twin" story, its representation of the personality of the inconvenient "double" is, however, unusual and striking. The novel also portrays the obsessive quality of scientific research, thus adding to the rich tradition of literary "mad scientists."