El doctor Frankenstein ensaya otro de sus diabólicos experimentos, tratando de dotar a sus criaturas de facultades intelectuales, robando el cerebro a seres humanos para dárselos a ellas. El doctor Cagliostro está decidido a dominar el mundo. Para lograr su propósito ordena asesinar al doctor Frankenstein y apoderarse de su tremendo monstruo, misión de la cual se encargan el siniestro Caronte y una extraña y sensual mujer-pájaro que se abalanza sobre Frankenstein. Contra este diabólico plan combate el doctor Seward que está dispuesto a todo con tal de acabar con el malvado Cagliostro.

Dr. Frankenstein attempts another of his diabolical experiments, trying to endow his creatures with intellectual faculties by stealing the brains of human beings and giving them to them. Dr. Cagliostro is determined to dominate the world. To achieve his goal, he orders the murder of Dr. Frankenstein and the seizure of his enormous monster, a mission entrusted to the sinister Charon and a strange, sensual bird-woman who pounces on Frankenstein. Dr. Seward fights against this diabolical plan and is prepared to do anything to stop the evil Cagliostro.