Marc, a young snake expert, works at a museum in Geneva. He loves snakes, to the point that he owns many and even takes a bath with his huge pet python. He meets and falls in love with a beautiful young woman named Malenka, who is the assistant--and mistress--of an older herpetologist professor. Marc discovers that not only is the "professor" a fraud but also a dangerous psychotic who had at one time seduced Marc's mother, and Marc believes that the longer Malenka stays with him, the greater danger she's in.

Marc vit avec sa mère dans un immeuble à Genève. Dans sa chambre, il possède une collection clandestine de reptiles vivants dont les plus beaux spécimens sont ceux que son père lui fait parvenir d'Afrique. Les serpents sont les êtres les plus importants de sa vie, jusqu'au jour où il rencontre Malika.