The Man They Could Not Hang

Dr. Henryk Savaard (Boris Karloff) and his assistant are performing an experiment on reviving recently deceased people through use of an artificial heart. Unfortunately, the assistant's girlfriend is scared and runs to the police. They arrive before Savaard can complete the experiment and the assistant dies. Savaard is convicted and executed for murder. However, another assistant uses the artificial heart to bring him back to life. But the good doctor is batspit crazy and out for blood. So he starts killing off those he holds responsible for his death one by one. The first of several movies Karloff made for Columbia where he played a mad scientist type out for revenge. It's formulaic but it works. Karloff carries the movie as always.