Don, Smokey and Whopper are are their way to Placer City where Don's brother Brad is U.S. Marshal. But when Don gets there, he finds that Marshal Brad is not his brother, but an impostor. When the deputy accuses them of being horse thieves, they flee town. When they go out to find Jenny, who they saved the day before, they are shot at and accused as gold thieves. But Jenny sets the miners straight and the boys, along with Mr. Robinson of the stage line, agree to work together to stop the gold thefts and find the real Marshal Brad.
