New research offers a plausible explanation for the Dyatlov Pass Incident, the mysterious 1959 death of nine hikers in the Ural Mountains in what was then the Soviet Union. In early October 2019, when an unknown caller rang Johan Gaume’s cell phone, he could hardly have imagined that he was about to confront one of the greatest mysteries in Soviet history. At the other end of the line, a journalist from The New York Times asked for his expert insight into a tragedy that had occurred 60 years earlier in Russia’s northern Ural Mountains—one that has since come to be known as the Dyatlov Pass Incident.