Three professional mountain climbers attempt to scale the Himalayan peak of Mount Meru, a big wall that even master climbers describe as nearly insurmountable. Jimmy Chin, one of the subjects, codirected with his wife, Elizabeth Chai Vasarhelyi, and much of the breathtaking natural imagery was shot by the climbers themselves. The three men withstand starvation, frostbite, and other ills as they climb various peaks; in the second half one of them returns to the quest after suffering an accident that leaves a hole in his skull and puts him at constant risk of a stroke.