Dennis O’Rourke’s documentary investigates the 1954 Castle Bravo hydrogen bomb test in the Marshall Islands and its long-term consequences. Combining declassified U.S. military footage, archival material, and interviews with Marshallese islanders and American servicemen, the film recounts how radioactive fallout affected residents of Rongelap and Utirik Atolls and explores the political and scientific context of Cold War nuclear testing.