Joseph Rouletabille is haunted by the memory of a woman who used to visit him when he was at boarding school many years ago. He can still recall the fragrance of her perfume and is convinced that this strange woman has some close connection with him. Before he can resolve this mystery, Rouletabille learns that his friend Mathilde Stangerson is in danger and rushes to her aid. Mathilde has just married her fiancé Robert Darzac and the couple are enjoying their honeymoon in the south of France. Rouletabille is incredulous when Mathilde claims to have caught a glimpse of her mortal enemy Larsan. The world knows that Larsan is dead, having died on stage when one of his escape acts went horribly wrong. If Larsan is alive then Mathilde has good reason to be afraid.