Physician Robert Briand runs a leper colony in the 15th century that takes in new residents who suffer from the ravages of syphilis. When the beautiful Marie-Blanche is brought to the grim, prison-like facility, Robert finds she displays no apparent signs of disease. He risks everything when he falls in love with the woman and makes plans to run away with her. Erland Josephson plays Robert's father, with Piera Degli Esposti as Robert's faithful assistant Terese.