The Pit and the Pendulum.

Seven students answer an advertisement to participate in an experiment to explore how the sensation of pain can be eliminated. Arriving at a secluded institute, they are welcomed by mysterious scientist JB Divay. Initially, JB's fascination with hypnosis, clocks and cactus plants are dismissed by the group as mere eccentricities. But as the students begin to disappear one by one, they begin to question JB's true intentions.