Professor Charles Conway (Carradine) is a Mad Scientist attempting to develop the proverbial Fountain of Youth by creating "the 17th gland". Ignoring all aspects of scientific ethics, Conway uses as his research subjects people who have no family and are under the impression that he can cure their depression. The research has been unsuccessful, however, and his subjects have all wound up as grotesque zombies. Some of Conway's patients begin to catch on to his scheme and intend to stop him.
- Hoist by Their Own Petard: Conway is stabbed to death by his earlier test subject Harry Jethro, who turns out to be Not Quite Dead.
- Mad Scientist: Professor Conway, of course.
- Ominous Pipe Organ: Conway treats his guest to the Toccata and Fugue on his living room Hammond.
- Public Domain Soundtrack: Several of the musical cues in this film would reappear in Bloodlust.
- Redemption Equals Death: Danny Green's first appearance is a temperamental one, abusing the other patients and Lobo. He only becomes truly sympathetic when he sacrifices himself in helping Mark escape.
- This Cannot Be!: Conway's response on seeing Harry Jethro coming to kill him is a horrified, "No! You're dead! I had you buried!"
- We Will Use Manual Labor in the Future: Conway has a bunch of cavemen in his basement, turning some sort of power turbine to keep his machines running. It's not made clear if they were his first failures or the source of his glands.