Breathtaking: K2 follows seasoned climbers Carla Perez and Adrian Ballinger as they attempt summiting “the savage mountain” without the aid of supplemental oxygen.

More people have traveled to space than have summited K2, the world’s second-highest peak that’s considered by many to be the Earth’s most challenging climb. Breathtaking: K2 follows seasoned climbers Carla Perez and Adrian Ballinger as they attempt summiting “the savage mountain” without the aid of supplemental oxygen — an expedition fraught with challenges that threaten not only their chance to reach the top, but also their lives.