In February 1959, nine experienced hikers set out on an expedition into the remote Ural Mountains of the Soviet Union.

They were young, skilled, and prepared for the harsh winter conditions. Their goal was simple: reach the mountain known as Otorten.

But they never made it back.

Weeks later, a search team discovered their abandoned tent on a snowy mountain pass. What they found made no sense.

The tent had been cut open from the inside. Footprints in the snow showed the group had fled into the freezing night — many of them barefoot or wearing almost nothing.

Then the bodies were found.

Some had died from exposure. Others had suffered massive internal injuries. One victim was missing her tongue.

No signs of a fight. No clea ...