This episode covers the story of nine experienced Russian hikers who died under suspicious circumstances in the Northern Ural Mountains between February 1st and February 2nd 1959.  

https://interestingengineering.com/the-mystery-of-the-dyatlov-pass-incident

https://en.wikipedia.org/wiki/Dyatlov_Pass_incident 

https://www.nationalgeographic.com/science/article/has-science-solved-history-greatest-adventure-mystery-dyatlov

https://dyatlovpass.com/cameras

https://www.amazon.com/Compelling-Force-Liam-Guillou/dp/B095SJJNQT