Dial M for Murder is a film directed by Alfred Hitchcock starring Grace Kelly, Ray Milland, and Robert Cummings, and released by Warner Brothers. The movie was based on the almost identical stage play of the same title by English playwright Frederick Knott.Tony Wendice is a former tennis player who married Margot partly for her money. To please his wife, he has given up tennis and now sells sports equipment. Margot once had a relationship with Mark Halliday, a crime writer for American TV, but broke it off when Mark went to the U.S. for a year. In time, they stopped writing to each other.
Tony and Margot have made their wills, naming each other as beneficiary. For a year, Tony meticulously plans Margot's murder. She has no idea that Tony knows of her love for Mark. He has gone to great lengths to steal a handbag containing one of Mark's letters, and even assumed the role of an anonymous Brixton-based blackmailer to find out whether she would pay to have it back.(She did, but he asked for only £50.) He even watched them having a little farewell party (eating spaghetti with mushrooms) in Mark's studio flat in Chelsea.
