Les murs ont des oreilles (1974)

A man who divorces buys a desirable new mansion in the country ;he discovers a wire-tapping set ,which enables him to spy on his children ,his servants,his secretary and even his editor(he is a best-selling writer,the toast of the town ,and women are dying for his autograph).Thus ,he discovers that his son puts on a show based on one of his works;that his editor is a crook ;that his wife he always love,has another flirt :he ridicules his rival during a shooting party.