The lost city of Kuma is ruled by the cruel, arrogant, beautiful queen, Ayesha, gifted with eternal life. She lures Leo Vincey into her world, seeing in him the reincarnation of the lover she long ago murdered in a fit of violent jealousy. Against all advice Leo is determined to stay and Ayesha persuades him to bathe in the flame of eternal youth... with disastrous consequences.

Teresa and Peter settle down in their new home after the wedding. Things are going well until her childhood furniture arrives, sending Teresa into horrible flashbacks of turmoil from memories of her youth.

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?