Knights of Heaven.

A military group of alpinists are selected to carry out a secret mission. The fate of humanity depends on their success. The rules of the mission require the death of each participant once his or her task is accomplished. After killing one of their colleagues and splitting into several groups, the alpinists continue their journey. But the human unconscious doesn’t follow military orders. Having once committed murder, the “knights” can’t control their desire to kill. They forgot their mission… and kill each other instead. —University of Pittsburgh