During World War II in Nazi Germany, a Kriegsmarine Officer, flanked by three Commandos, barges into the laboratory of a Dr. Riesendorf with orders to seize the immortal heart of the Frankenstein Monster, on which Riesendorf is busy experimenting. The heart is transported by U-boat and passed on to a Japanese Imperial Navy submarine, who take it back to Hiroshima for further experimentation. But just as the experiments are about to begin, Hiroshima is bombed with a nuclear weapon by the Allied Forces.