In Mongolia’s coldest valley, horses mean life. But in the Iron Winter, nothing can survive alone.

For countless generations, the herders of the Tsakhir Valley have protected their horses from ferocious arctic storms by amassing a giant winter herd, nominating their bravest young men to protect it.

The daring tradition served as a brutal coming of age ritual, until five years ago, when under increasing environmental pressure, it abruptly ended. Fearful about the loss of culture, elders soon vowed to revive it. And two young friends were handed the daunting responsibility to not only protect the valley’s herd, but to save its most sacred practice.

For four months, the boys battle Mongolia’s deadliest winter on record, testing friendship and faith in a fight to keep 2000 horses alive, and preserve an ancient way of life.