Beside a rain-swollen river in Patagonia, a man approached on a horse. His mount, a rusty red beauty, sported the short-trimmed mane and neatly squared-off tail of a well-kept horse. The man wore goatskin chaps, a woolen poncho, and the jaunty black beret typical of the region. This pair belonged to this place in a way I could only dream of.

The man stared at us. We were up to our knees in mud and dwarfed by huge backpacks. It was apparent we had money, but we had no horses.

"Por qué no tienes caballos?" he asked as he rode into the river.

At that moment I knew. I wanted to travel this country like the people who lived there. I wanted to know this place as only one on horseback could.

As a novice horsewoman, Nancy Pfeiffer took off across Patagonia alone on horseback. Over the next two decades and three thousand kilometers of rugged horse trail, the hospitable people who live there took her in, and Patagonia slipped silently into her soul. As if watching a beloved child grow up, Nancy bore witness to the subtle, yet disturbing, changes barreling down on Patagonia.