A down-on-his-luck surgeon agrees to assist a brilliant but unethical doctor's brain experiments in exchange for the promise of curing his condemned fiancée, only to discover his mentor has been using a rare drug to fake the deaths of surgical subjects so he can operate on their brains — creating a houseful of shambling, disfigured failures locked away in his basement. Horror ensemble picture stacking together Basil Rathbone, Bela Lugosi (in his final American screen role), Lon Chaney Jr., John Carradine, and Akim Tamiroff.