Playwright Neil Simon tries his hand at film parody in The Cheap Detective, sending up the private genre of the 1940s --The Maltese Falcon in particular. Peter Falk is Lou Peckinpaugh, a trenchcoated nincompoop with a Humphrey Bogart accent, who finds himself accused of killing his partner, with whose wife Georgia Merkle (Marsha Mason) he has been having an affair. Amidst this confusion, the sultry Mrs. Montenegro (Madeline Khan) stumbles into Lou's office. She is searching for an ancient treasure --a dozen diamond eggs. Soon Lou finds himself having to deal with a collection of unsavory characters --Jasper Blubber (John Houseman), "The Boy" (Paul Williams), Pepe Damascus (Dom DeLuise)-- who are also looking for the diamond eggs.