Dr. Maria Frankenstein (Narda Onyx), granddaughter of Victor Frankenstein, is experimenting in a castle above a small desert town.
The same day, Jesse James and his gang rides into town after being double-crossed during a stage coach robbery. His partner Hank (Cal Bolder) is injured, and Jesse meets Juanita (Estelita Rodriguez) who takes him to the castle Frankenstein to be nursed back to health.
While Jesse and Juanita are in the village getting medicine, Maria switches Hank's brain out for another, turning him into a monster and renaming him Igor.
When Jesse returns, he and Juanita are the only ones who can stop the doctor and monster and save the village.