Ranch owner Billy Porter leaves the wilderness to seek his fortune in San Francisco, California, with his plans for an improved automobile engine. Once in the city, Billy is cheated out of his money, but he is befriended by a lame newsboy named Jim McClusky, and his father, prizefighter Knockout McClusky. Billy trains Knockout for an important bout against "Tiger" Doran, and bets $5,000 on his friend to win. He later meets Pearl Matthews when he stops her runaway horses in a park. On the night of the boxing match, Billy discovers that Knockout has been drugged. With the aid of automobile manufacturer John B. Prescott, Billy enters the ring and defeats Tiger. He also discovers that John is his long-lost father, who initially invited Billy to go west. After perfecting his motor, Billy enters his car in a race, which he wins, along with Pearl's love.