On January 3, 1961, nuclear reactor SL-1 exploded in rural Idaho, spreading radioactive contamination over thousands of acres and killing three men. The army blamed “human error” and a sordid love triangle. Though overshadowed by Three Mile Island, SL-1 remains the only fatal nuclear reactor incident in American history. Todd Tucker, who first heard the rumors about the Idaho Falls explosion as a trainee in the navy’s nuclear program, suspected there was more to the accident than rumors suggested. Poring over hundreds of pages of primary sources and interviewing survivors revealed that the army and its contractors had deliberately obscured the true cause of the accident, which resulted from poor engineering as much as uncontrolled passions. The National Reactor Testing Station, where the meltdown occurred, had been a proving ground where engineers, generals, and admirals attempted to realize the Atomic Age dream of unlimited power—amid the frantic race for nuclear power between the army, the navy, and the air force. The fruit of those ambitious plans included that of the nation’s unofficial nuclear patriarch, Admiral Rickover, whose “true submarine,” the USS Nautilus, would forever change naval warfare. But with the meltdown in Idaho came the end of the army’s program and the beginning of the navy’s long-standing monopoly on military nuclear power. Atomic America provides a fast-paced narrative history, advocating caution and accountability in harnessing nuclear energy.