The Cheap Detective (1978)

Synopsis
Spoofing the entire 1940s detective genre, and his own performances as a bumbling private detective, Peter Falk plays Lou Pekinpaugh, a San Francisco private detective accused of murdering his partner at the instigation of his mistress, the partner's wife, Georgia Merkle (Marsha Mason). Police Lieutenant DiMaggio (Vic Tayback) has his eye on Lou and blunders around in a way which complicates Lou's efforts to clear his name. Lou gets a new client when Mrs. Montenegro (Madeline Kahn) and her cronies (John Housman, Paul Williams and Dom DeLuise) hire him to search out a dozen diamond eggs. Marlene DuChard (Louise Fletcher) also comes to him for help of a complicated nature. In this madcap comedy written by Neil Simon, obstacles and complications appear every few minutes, and a great many famous actors show up in hilarious cameos. ~ Clarke Fountain, All Movie Guide