A Day at the Races is probably the last universally loved Marx Brothers movie, chronologically speaking.
The story sees Groucho in the role of a veterinarian who has been brought in to treat a wealthy and eccentric human at a sanitarium, played by the Marx Brothers’ frequent straight woman, Margaret Dumont.
The only way to save the sanitarium is to bet everything on a horse and hope it wins.
Of course, the codebook requires a master codebook to be useful, and I bet you can guess who can sell you one of those.