Neil Simon's screenplay is a clever spoof on murder mysteries in which eccentric millionaire Lionel Twain (Truman Capote) invites the world's greatest detectives to his home and challenges them to solve the perfect murder. Among the sleuths that try to solve the case are Milo Perrier (James Coco), Sam Diamond (Peter Falk), Jessica Marbles (Elsa Lanchester), Dick and Dora Charleston (David Niven and Maggie Smith), and Sidney Wang (Peter Sellers), all of whom are easy-to-guess but altogether sharp parodies of beloved literary characters.