Olivier, a young, unemployed man from the province, arrives in Paris and hooks up with Mario, a shady character, who gives him a job selling art books door-to-door. They meet Ariane, a young woman living alone on the 5th floor of an old apartment building. She tells them about the empty apartment below hers and they return that same evening to break into it, only to discover that the apartment is, in fact, being used by a professional domina where she holds her victims captive. And then they’re caught in the act by a leather-clad Ariane when she descends a hidden staircase that links the two apartments. She lets them go, but in exchange, she exacts a small ‘service’ from Olivier …