In February 1959, a group of nine hikers in the Russian Ural Mountains died in a mysterious fashion on the eastern side of an elevation known as Dead Mountain. Eerie aspects of the incident — unsettling and unexplained causes of death, a strange final photograph by one of the hikers and signs of radioactivity — have led to decades of speculation over what really happened. This gripping work of literary nonfiction delves into the mystery through unprecedented access to the hikers' own journals and photographs (many translated and reproduced in the book); unseen government records; and dozens of interviews, including with the only surviving hiker; and the author's retracing the hikers' fateful journey.