The Dyatlov Pass incident was an event in which nine Soviet hikers died in the northern Ural Mountains in February 1959, under mysterious circumstances. When a search party finally found the mutilated bodies of the missing hikers, the scene was so horrifying and so confounding that it would inspire conspiracy theories for decades to come. Who - or what - killed the young and extremely experienced hikers, in a place that's been called 'Russia's Area 51'?