Seventy-five years ago on 6 August, the United States dropped a nuclear bomb on Hiroshima, Japan. Up to 120,000 people died in the bombing and its aftermath. Some of the survivors, known as hibakusha, would eventually enroll in the Radiation Effects Research Foundation’s Life Span Study, which continues to examine the effects of atomic radiation on the human body. The study’s findings have been the basis for radiation safety standards around the world, ranging from power plants to hospitals. Decades of archival footage and images, survivor drawings, and the testimony of research participant Kunihiko Iida convey the kind of misery that results from an atomic bombing—as well as the message of peace and humanity that can result from scientific research.