When the episode begins, Hopalong arrives in Mexico at the home of Colonel Gonzalez, as he received a note from Gonzalez saying he wanted to meet him there. However, the note is fake...and at the same time, Gonzalez received word that Hoppy wanted to meet him...in the desert! However, they both are being manipulated by Zorro, 'the Fox', a bandit that Gonzalez and Cassidy sent to prison some time ago. But Zorro has escaped and now wants to kill both these men...and he soon dispatches Gonzalez. What no one realizes is that Zorro's evil sister is staying with the Gonzalez family....and she is trying to seduce Cassidy in order to maneuver him into harm's way.
This is a good but not great movie. Much of it is because both Cassidy's buddy, Lucky AND the Colonel's sister, Anita, are incredibly stupid characters...too stupid. As a result, Hoppy not only has to solve the crime but keep these two from getting killed in the process! Still, enjoyable and an amiable time passer.