Groucho Marx, King Of The Jungle

Frank Denby and Groucho Marx arrive on the set of the new Ty-Gor film, a Tarzan knockoff, expecting to have Groucho do his humorous walk-on. What they find is that Randy Spellman, the star of the picture, has been murdered. Frank's wife, Jane, is only a few weeks away from having their baby, and the amateur detective team has promised to lay off on the sleuthing. But when a stuntwoman who has gone missing is suspected of the murder, Jane insists they take up the case to clear the young woman's name.
In addition to being a horrible actor, Spellman was a womanizer and a blackmailer. Many people had reason to dislike him, or even kill him, and the investigation leads Frank and Groucho through the glamour and seediness of 1940s Hollywood, Groucho signing autographs all the while.