Olivier Martin (Rollin’s real-life half-brother) comes to the aid of mute Caroline François; his loyalties are soon divided between this apparently immortal bloodsucker and the sinister cabal headed by Maurice Lemaître, with minions including the twin Castel sisters, which aims to dissect the young woman. Rollin takes full advantage of a color palette in his first non-black-and-white feature, commencing a fruitful collaboration with cinematographer Jean-Jacques Renon.