Doctor Satan Versus Black Magic

Doctor Satan Versus Black Magic (original title Dr. Satán y la magia negra) is a 1968 Mexican horror movie about an evil demon (Joaquin Cordero) who battles an ancient vampire (Noe Murayama) for control of a formula capable of transforming any metal into gold. The film costars Aurora Clavel, Nathaniel Leon, Sonia Furio, and Luz Maria Aguilar. It is a sequel to the 1966 movie Doctor Satan, also starring Cordero.

Plot Summary
In Hell, Doctor Satan is tasked with returning to Earth and obtaining a formula that is currently held by Lei Yin, a centuries-old vampire. Yin, a scientist, has developed a large ray-gun that, in conjunction with the formula, will allow him to turn any metal into gold. Doctor Satan's orders are to take over Yin's operation and produce enough gold to become the richest and most powerful person on Earth, handing control over the planet to Lucifer himself. Once on Earth, Doctor Satan opens an office that serves as a front for his secret laboratory. He holds job interviews for secretaries, and hypnotizes them into following him into his laboratory. There, he injects them with a serum that turns them into his mindless servants.