During World War I, Rin-Tin-Tin finds that he must rescue his master, a fighter pilot, from his wrecked aircraft. He also has to help him escape his rival, who has ordered him shot so he can have the girl they're competing for all to himself.
A train engineer and his fireman are best friends until the engineer breaks up a romance between his pal and a trampy girl he knows is no good for him, which also breaks up their friendship.
