Before managing to reach El Morisco, Eusebio and the Broncos Apaches decimated by the terrible Guaimas, the wolf man of the Sierras, the pards must face hordes of famished wolves which, through magic, obey the orders of the diablera Mitla. But slaughtering the powerful lycanthrope is not an easy undertaking: tens of arrows and caliber 45 bullets are needed to beat his diabolical strength. And instead a very poisonous snake unexpectedly kills Mitla, at the bottom of the gloomy caverns where she was gathering the noxious flowers capable of changing her brother into a werewolf!