An outlaw gang robs Virginia City's bank and makes off with almost all of its money. The youngest member of the gang manages to get a job on the Ponderosa as a bronc buster with the intention of informing the bank robbers of any posses that may threaten their hideout. While Ben, Adam and Hoss welcome the newcomer, Little Joe becomes suspicious of his activities

After a U.S. deputy marshal apparently saves Adam's life by gunning down two men who shot at him, he eventually reveals that he is in town to bring a close friend of the Cartwrights to San Francisco to testify in a statewide racketeering trial, but the Deputy Marshal's motives soon become suspect as to what he really wants to do with the reluctant witness.