When the U.S. government learns that a western medicine show may be a front for some illegal activities, they send an agent who calls himself John Wyatt (John Wayne) to investigate. Wyatt begins to trace counterfeiting and illegal alcohol distribution that seems to be part of the show put on by old Doc Carter (Earle Hodgins). The traveling medicine show features the sale of “medicine” with 90% alcohol. Wyatt is handy with a gun and joins the show as a trick gunslinger who can shoot out candles as part of his act. Wyatt soon discovers that the true culprit is probably Doc’s former partner, the untrustworthy Curly Joe (Yakima Canutt).