In June 1970, the Messner brothers reached the peak of Nanga Parbat after a gruelling climb up the Rupal face. At the top, 23-year-old Günther suffered from symptoms of mountain sickness and felt he could not descend along the same route. Therefore, 26-year-old Reinhold led them down the more forgiving Diamir face. During their descent, the younger of the two brothers disappeared, probably swept away by an avalanche. Reinhold looked for him, but in vain, and made the rest of the descent alone. He returned to base camp after six days with serious frostbite to his feet and was unjustly accused of having sacrificed his brother to reach the top. Forty years later, the film retraces the key episodes in that dramatic story.