Marianne and Jacques are a young middle-class couple who live in a chic Parisian apartment with their two young children. One day, Marianne receives an unexpected visit from two strangers, Mr and Mrs Worms, who claim to have lived in the apartment when they were children and who ask if they can just take a look around their former home. Marianne agrees, but no sooner have the mysterious Worms left than things take an inexplicable turn for the worse...
The film follows the villain “The Serpent” in his fight to conquer the world at any cost. Close to the best B series, Yaccelini runs through its plot of scientists, chases and highly suspenseful endings, aware that the most intense adventure is the one that never manages to hit the brakes.
When her husband's arrest leaves her penniless, a woman accepts an invitation to move in with a strange couple.
During an orgy, Some old and wealthy notables are being murdered by a small group of leftist young revolutionaries. Very soon the police are tracking down Virgile Cabral, the leader of the group. Meanwhile, Virgile's brother and only relative, Vincent, a violinist (and a thief), comes back to Paris. They have not seen each other for three years. Vincent does not believe in the revolution. He only tries to live as he wishes to live. But by looking for his hunted down brother, he has no other choice than to be involved in a fight that is not his.