In 1959, after a group of nine student hikers are found dead in the Ural Mountains, KGB Major Oleg Kostin is sent to investigate. During the autopsy, Oleg has a flashback of a disturbing memory from WWII.

Oleg heads to Moscow to look further into the file of Alexander Zolotarev, the oldest member of the group, and makes a surprising discovery about his body.

As the hikers prepare for ascension, an ominous wind engulfs them, followed by an astonishing sight in the sky; perplexed, the group begins to remember the words of the Mansi locals before receiving one more warning.

Tempalov and the searchers examine the scene of the group's death, finding multiple confounding details that inspire different theories; Kostin shows his superiors a report that details strange objects in the sky, and a crucial discovery is made.

Kostin attempts get to closer the Dyatlov's case. He learns about the prison fugitives and attempts to find out whether this encounter was fatal for the tourists. Kostin decides to confess his feelings to Katya.

Nine days before the group's death, the hikers pass through a small village where they learn about the region's Indigenous Mansi people, who have named the mountain they're headed toward the Dead Mountain.

The hikers search for a strange figure in the woods and take him back to camp; Zolotarev is suspicious of the new guy.

The group reaches the pass and sets up camp. As the night progresses, the conditions worsen and their struggle becomes unthinkable. Each harrowing detail fills in the puzzle pieces of what really happened to the Dyatlov hikers.