Part police thriller and part exploration of the dark side of men's attitudes about women, Hygiene de l'assassin concerns a young female journalist, Nina (Barbara Schulz). Nina has scored a plumb assignment, an interview with Tach (Jean Yanne), a well-known but reculsive novelist who rarely speaks to the press. After he passes along his less-than-charitable views about women (including the belief they should be killed in childhood, before they start to menstruate), Nina concludes the interview, but soon finds herself interrogated by police when Tach is found dead and she is the key suspect.