In 1959, nine hikers died under baffling circumstances in the Ural Mountains. Their tent was torn from the inside, and bodies were found inadequately dressed in freezing conditions.

In February 1959, a group of nine hikers, mostly students from the Ural Polytechnic Institute, set out for Mount Otorten in the northern Ural Mountains. When they failed to return by February 26, a search party was dispatched. The group's tent was found torn open from the inside, and the bodies were discovered up to 1.5 kilometers away, inadequately dressed despite temperatures of -30 degrees Celsius.
The first five bodies found were determined to have died from hypothermia, but four others, discovered months later beneath a snow ridge, had severe injuries: three had major bone fractures. Lyudmila Dubinina was missing her tongue and eyes. Abnormal levels of radioactive contamination were detected on some clothing.
Soviet authorities concluded the deaths were caused by "a compelling natural force" but offered no specifics. The case files were classified and remained sealed until the 1990s.