In attempting to develop a chemical which would make a person super-intelligent, Dr. Montrose fails and the subjects of his experiments metamorphose into hideous monsters who band together and prey on humans. With the police stymied, a young detective attempts to track down the leader of the group of killers, known only to have a small crimson stain in one eye.
A mad doctor attains the dead body of a racketeer who was recently murdered by a rival mobster. The doctor has a bizarre and sinister experiment in mind...he intends to use the corpse as a vessel to resurrect one of the Knights Templar from the time of the Christian Crusades.