Three Smart Saps.

The stooges are engaged to the three daughters of a prison warden. When they learn that some crooks have taken over the prison and their prospective father-in-law has been locked up, they decide to go undercover to rescue him. The stooges sneak into the prison where they find a casino with a fancy party in progress. After swiping some formal attire, they crash the party and get candid camera evidence to expose the crooked goings-on. With the crooks behind bars once again, the stooges are able to get married and all ends well.