(WARNING: Major spoilers abound!)
Charlie is walking his bulldog after their meager lunch, when he sees a sign asking for sparring partners for a local boxer. Charlie hesitates to answer the ad, but when he sees a horseshoe on the ground, he picks it up and takes it with him as a sign of good luck. When sparring partners ahead of him get knocked out instantly, Charlie slips the horseshoe into one of his boxing gloves, whereupon he knocks out the boxer. Charlie is put into training for a bout against the champion (Bud Jamison) and impresses the trainer’s daughter (Edna Purviance at her curviest).
Strange elements abound. As a “character,” the bulldog is rather superfluous (except for the ending – more on that in a minute), and the climactic boxing match itself is based more on spot-gags than characterization; both of these are situations that Chaplin would later rectify in, respectively, A Dog’s Life and City Lights.
The really strange thing is that, as much as we want to root for Charlie, it’s “cheating” that makes him a champion, not skill or luck. We know perfectly well that the only reason he knocks out the boxer (and several innocent bystanders) is because his glove is loaded down with that horseshoe (a plot point, by the way, that is completely shrugged off in the climactic fight). And the only reason that Charlie wins the fight (and that the meandering fight finally ends) is that Charlie’s bulldog enters the ring and buries his teeth in the champion’s behind.
Nevertheless, a lot of funny stuff throughout, as when Charlie’s trainer tells him to jog and he merely does a faster version of his usual waddle. You’ll get some good laughs from the movie, as long as you leave logic behind.