There are certain stories that stay with you. The haunting tale of the Dyatlov incident is one of them.

In some ways the story is simple. In 1959 a group of eight experienced hikers went on a winter expedition in the Ural mountains of Western Russia. Twenty-four days after they set off, they were all found dead of hypothermia. While a tragedy, it isn’t necessarily a story that you think would still be told over 50 years later. It is the details of the case that make it so mysterious and so compelling. 

At the heart of the case is this: the hikers didn’t get lost. Analysis of the scene found they were all safe and sound inside their tent when something caused them to panic. Whatever it was worried them so much that they cut their way out their tent. They hikers all fled into the freezing dark night without hats, clothes, or shoes. 

The details only get more bizarre from there. Mysterious light in the sky, bodies giving off radiation,  remains found with bizarre injuries. The USSR kept the investigation files secret until the 1990s, when it released documents concluding the hikers died of “a compelling unknown force.” Conspiracy theorists have had a field day proposing everything from a Yeti attack to secret weapons testing.

Recently a new theory, more firmly grounded in science, was proposed. Involving something called “infrasound,” it may finally explain what led those eight hikers to flee their tent. We examine the theory, and the whole perplexing Dyatlov incident, in this edition of 100 Wonders.