The head of a major cosmetics company experiments on herself with a youth formula made from royal jelly extracted from wasps, but the formula's side effects have deadly consequences.

A physician on death row for a mercy killing is allowed to experiment on a serum using a criminals' blood, but secretly tests it on himself. He gets a pardon, but finds out he's become a Jekyll-&-Hyde.

Dr. Frankenstein and her assistant, Dr. Yanco, are going to bring one of their experiments to life in Santo Vs. Frankenstein's Daughter. She intends to use a monster named Ursus to do her evil bidding. Using a youth serum to retain their vitality, the doctors set their sights upon none other than El Santo. They need his super human blood to regenerate a stronger youth serum. They kidnap Santo's goddaughter, Norma and lure him into Dr. Frankenstein's lab where he is captured and enslaved. Will Santo make it out alive?