Philippe Tardieu lives with his mother, Christine, and two sisters, Sophie and Patricia, in the suburbs of Nantes and works as a salesman. Christine does hairdressing at home to earn some spare change. Sophie, the eldest sister, is getting married to Jacky. As for Patricia, the youngest sister, she tries as best she can to escape she's not sure what. At the wedding Philippe falls in love with Senta, one of the bridesmaids. It is love at first sight and, soon, Philippe spends all his nights with Senta, neglecting his mother and his younger sister. Senta's love is very exclusive and demanding. One day, she tells Philippe that, if he really loves her, he should kill a man, any man, for her. The next day, in order to please Senta and as a joke, Philippe says to her that he's responsible for the murder of a down-and-out. Senta believes him and says that she will do the same for him. When the corpse of another man is found, a panicking Philippe starts to wonder.