WE ARE MOVING THROUGH A MYSTERY. Whiteness envelops us. We can't see where we are going. We can't see what lies to our left or right. Our only guide is ascent: We climb the fall line, crampon points and ice-ax picks skittering on verglas-glazed rock. There are just two of us on this expedition: taciturn Louisiana man Ross Lynn, 26, and yours truly. We're in a cirque with no name in the Daxue Shan Range, on the far eastern edge of the Tibetan plateau. It has been my personal dream to come here and climb. There are no rescue choppers or Sherpas, cells phones don't work, the nearest hospital is days away. Ross and I are on our own, inside the unknown.

We can't see them, but from the map we know there are four unclimbed 20,000-foot summits looming above us. We're hoping to climb just one, 20,059-foot Nyambo Konka.

A squall swoops in, hail rattling upon our helmets like gravel.

"Can't see a damn thing!" I shout.

But the higher we go on the mountain, the more sunshine begins to break through. Within an hour, the 4,000-foot visage of Nyambo is staring down on us. Blind to the terrain above, we've managed to climb right up beneath a deeply fractured, quarter-mile-long hanging glacier—something like wandering into a building that's about to be dynamited.

Ross and I make an abrupt right-angle turn, hustle across a vast, telltale fan of avalanche debris, and descend via a safer route on the north side of the cirque.

"Let's not do that again," I say on the way down.

"Scratch Plan A," Ross agrees.

In the morning we move our camp higher. Plan B is to climb the central couloir, which we discover, to our alarm, is running with avalanches. On to Plan C: Ascend another couloir farther north.

We dig out a tent platform we believe to be safe from avalanche. Erect the tiny tent, eat cubes of yak gristle, drink Chinese tea, load our packs for the morning attempt, scootch into our sleeping bags, talk.

Ross is regaling me with his ascent of Lurking Fear, a notorious route on Yosemite's El Cap, when an ominous roar drowns out his voice. Our tent is being pummeled and bashed in, and Ross and I are screaming and tearing at the tent zippers, diving out into the darkness clawing bare-handed and sock-footed to safety. After the avalanche passes, we find our tent partially flattened, a softball-size rock having sliced through the fly.

"Perhaps we should move camp," Ross says in his calm drawl.

We spend the next two hours digging out a new tent platform by headlamp, only to have an avalanche sweep by on the opposite side the moment we're back in our bags.

"Busy place," I say.

Neither of us sleep that night. We listen, like infantry soldiers in a trench, ears straining to interpret the portent of each explosion. We don't talk much; we wait. We wait to see if we survive. We wait for dawn and Plan D.