Cab driver Wilbur Hoolihan accidentally kills a hack horse owned by King O'Hara and his daughter, Princess O’Hara, by feeding it candy.

Wilbur and Grover manage to find O'Hara and hide Tea Biscuit in their hotel room, but they are hounded by the house detective, Warner, who was tipped off by the touts.

The three touts and Warner converge on the track and confront Grover, who makes a deal with them to turn over the horse Wilbur riding for $100.

It Ain't Hay is based upon the Damon Runyon story, Princess O'Hara, which Universal first made into a film in 1935 with Chester Morris.

It Ain't Hay was released on DVD on October 28, 2008 as part of Abbott and Costello: The Complete Universal Pictures Collection.

The film's studio-authorized DVD release had been delayed for many years due to legal issues with the estate of Damon Runyon.