What's more dangerous than scaling Mount Everest? For mountaineer Pete Athans, the answer lies in the ancient kingdom of Mustang, a remote part of the Asian nation of Nepal. Long-abandoned caves built high into steep cliffs contain amazing treasures--and pose incredible dangers. Reaching these "sky caves" safely takes guts, smarts, and luck. And then there's the question of what to do with a two-thousand-year-old human skull. . .
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