2003年夏天,一群牧羊人赶着羊群,最后一次通过美国最西北方蒙大拿州的熊牙山山脉。这是一条将近300千米的路程,沿途是积雪覆盖岔道众多的绿色山谷,一路上他们需要穿越道路狭窄危机遍布的山脊。年老的牧羊人尽全力使数以百计的羊不至走失,免受丛林里饥饿的狼群与大灰熊的威胁。In the summer of 2003, a group of shepherds took a herd of sheep one final time through the Beartooth Mountains of Montana, in the extreme north-west of the United States. It was a journey of almost three hundred kilometres through expansive green valleys, by fields of snow, and across hazardous, narrow ridges - a journey brimming with challenges. The aging shepherds do their very best to keep the hundreds of sheep together; the panoramic high mountains are teeming with hungry wolves and grizzly bears.