India, Dec. 15 -- At the height of the Cold War in 1965, China's first atomic test sent alarm bells ringing in Washington.

Keen to monitor Chinese missile activity deep inside Tibet, theCIAdevised an audacious plan: plant a nuclear-powered surveillance antenna atop one of India's tallest Himalayan peaks, with a clear line of sight into Chinese territory. The chosen mountain wasNanda Devi, towering above the Indo-Tibetan frontier.

What followed was a covert operation that combined espionage, high-altitude mountaineering and nuclear risk-ending with a plutonium device disappearing into the ice, never to be recovered.

The idea reportedly took shape at a cocktail party, where US Air Force chief General Curtis LeMay spoke with Barry Bishop,...