I'm Not Going To Be Able To Sleep Tonight (Part 2)

Wiki:

The Dyatlov Pass incident refers to a mysterious event that resulted in the deaths of nine ski hikers in the northern Ural mountains. The incident happened on the night of February 2, 1959 on the east shoulder of the mountain Kholat Syakhl (Холат Сяхл) (a Mansi name, meaning Mountain of the Dead). The mountain pass where the accident occurred has been named Dyatlov Pass (Перевал Дятлова) after the group's leader, Igor Dyatlov (Игорь Дятлов).

The mysterious circumstances and subsequent investigations of the hikers' deaths have inspired much speculation. Investigations of the deaths suggest that the hikers tore open their tent from within, departing barefoot in heavy snow; while the corpses show no signs of struggle, one victim had a fractured skull, two had broken ribs, and one was missing her tongue The victims' clothing contained high levels of radiation. Soviet investigators determined only that "a compelling unknown force" had caused the deaths, barring entry to the area for years thereafter. The causes of the accident remain unclear.

[Here's Mark Forford on the incident]