"The Fox" (Paul Sutton) is out for revenge and lures Hoppy across the border via a letter from an old friend into Mexico. Hoppy finds that his friend has been murdered and had left a partial message written in the sand, "Zorro", Spanish for Fox. Hoppy, who had captured "The Fox" in "Borderland", whilst working undercover for both the U.S. and Mexican governments; the Fox had been leading raids on both sides of the border.
Morris Ankrum aka Stephen Morris played "The Fox" in "Borderland". Paul Sutton does a fine job as "The Fox"; but for the sake of continuity I would have preferred Morris Ankrum in the role.
This one is a little more violent than the majority of "Hoppy" pictures but not unnecessarily so, it also has the benefit of a good plot and the story moves along nicely; and "Hoppy", "Lucky" (Russell Hayden) and "Windy" (George "Gabby" Hayes) are in fine form as are the rest of the cast. Highly recommended. See Borderland first, if you can.