"Nine young students go on a skiing holiday in Russia’s Ural Mountains but never return. Eventually, their bodies are discovered – five of them frozen to death near their tent, four more bearing mysterious injuries – a smashed head, a missing tongue – buried in the snow some distance away.
All, it seems, had fled in sudden terror from their camp in the middle of the night. Casting aside skis, food and warm coats, they dashed headlong down a snowy slope toward a thick forest, where they stood no chance of surviving bitter temperatures of around –30º C (–22º F).
At the time, seemingly baffled investigators offered the non-explanation that the group had died as a result of “a compelling unknown force” – and then simply closed the case and filed it as Top Secret."