What begins as an honest effort at discovering a cure for polio, ends up becoming a frenzied quest costing innocent lives. When the good doctor Bernard Adrian (Boris Karloff) finds that the cure depends upon sizable amounts of serum found only in upper primate spinal columns, he goes a little overboard and kills an escaped circus ape and goes about murdering local folks to get the precious fluid. His mission is maddened because he has recently suffered the loss of his beloved daughter. Not one of Karloff's premier efforts, this one will probably please only his ardent admirers.