The 1927 Hitchcock boxing film described as his only original screenplay was The Ring.
The Ring is a British silent film about Jack “One-Round” Sander, a fairground boxer who challenges the Australian heavyweight champion Bob Corby after losing to him. The rivalry becomes personal when Corby grows close to Jack’s girlfriend, Mabel, and the story builds toward a championship fight.
Hitchcock drew inspiration from his regular attendance at boxing matches in London. He noticed details he later incorporated into the film, including the varied social backgrounds of spectators and the custom of sprinkling fighters with champagne after rounds. The film was made for British International Pictures and starred Carl Brisson, Lillian Hall-Davis, and Ian Hunter.
“The Ring” is commonly called Hitchcock’s only original screenplay, but that label needs a qualification: Eliot Stannard had uncredited input. Hitchcock’s other silent films listed here—The Farmer’s Wife, Easy Virtue, and Downhill—were adaptations, making The Ring the clear quiz answer.