A group of "ghostly" conquistadors has been robbing towns along the Mexican border. West and Gordon follow their trail across the border to San Pedro, where they learn that the raiders are using a secret pass in the mountains to reach a hidden valley. Upon riding out there they encounter and rescue Juan Ramirez and his daughter, Cosina. The two are residents of Buena Vista, a town in the hidden valley which sits in the shadow of a volcano inhabited by the conquistadors and their leader, the white "god" Cortez. Cosina guides the agents to the village and they set about ending Cortez's reign of terror.
Tropes present in this episode:
- And Now You Must Marry Me: Cortez forces Cosina to marry him by threatening to have her father worked to death in his mercury mine.
- Appease the Volcano God: Those chosen to be "sacrificed" are actually put to work as slave labor in the mercury mines under the volcano.
- God Guise: A group of criminals pretend to be both the immortal Cortez and his conquistadors and the representatives of the local volcano god in order to rule a small Mexican village with impunity.
- Mugged for Disguise: Jim "borrows" the uniform of a treasure wagon driver in order to sneak into the volcano.
- Scooby-Doo Hoax: The criminals put on a pretty good show when pretending to be the spirits of Cortez and his men. It frightens the locals away, but Jim and Artie are not so easily deceived.
- Volcano Lair: Cortez's base is located within the volcano.