The Plaza Hotel had a special place in my heart, until much of it was turned into condos. When the Beatles came to the U.S. the first time and stayed at the Plaza, my dad and I dropped by to share in the excitement—and, knowing him, to prove his theory that "authority is 98% assumed, 2% delegated," as we passed through the police barricades unchallenged. Of course, the story might have been different if we'd been squealing teenage girls, of which there were hundreds assembled across the street.

Fernando Alvarez, above, sells items made from qiviuk. Rob Bennett for The Wall Street Journal

We never got to see the Beatles during the few minutes we loitered in the lobby. But when we emerged from the hotel, a shout went up from the crowd—they were obviously primed to scream at anything—giving me an experience I'll always prize.

So it was more than a little depressing when I returned to the Plaza after its 2008 renovation and found the once-teeming lobby virtually deserted, the Palm Court closed. Its new underground luxury shopping mall only seemed to underline the misfortune of the renovation, though I have to confess I was drawn back on several occasions by Demel, the Viennese pastry shop, which took up residence there briefly.

Once Demel departed, the Plaza was again dead to me. Until last week. That's when I returned, at my wife's suggestion, to visit Qiviuk, a clothing shop that since 2008 has been a member of the hotel's basement "Plaza Retail Collection." I guess I missed it on my forays to Demel for Sachertorte since it's stuck in a corner and because, frankly, $1,200 ladies' cashmere sweaters aren't in my budget. Except they aren't cashmere; they're qiviuk—which is why my wife thought I might be interested.

You may wonder: What is qiviuk (pronounced kiv-ee-uk)? It's the undercoat that musk ox, which have been around since the last Ice Age (apparently having survived it better than its contemporary, the wooly mammoth), shed as they frolic in the frozen north. Harvested by the Inuvialuit, people indigenous to Canada's High Arctic, the material is said to be softer and lighter than cashmere and warmer than wool. I can't vouch for that except to say the garments I handled—they include everything from somewhat affordable $105 headbands to $3,400 blankets—felt awfully soft and luxurious to me.

An item made from qiviuk. Rob Bennett for The Wall Street Journal

Merchandizing the fabric has been the brainchild of Fernando Alvarez, a Peruvian who has lived in Canada for the last 24 years, where he owns several qiviuk clothing shops. Mr. Alvarez, who happened to be present the day I visited, told me that he discovered the fiber when a scientist friend summoned him to the University of Saskatchewan, where they were studying several musk ox sent down by the Inuvialuit.

The animals were apparently shedding like crazy, and the scientist thought that if anyone could transform the detritus into a commodity it would be Mr. Alvarez, who knew his way around alpaca, having dealt with the local communities who raised them in his native Peru. "I saw enormous potential," he recalled. "I'd never seen anything as light, like a cloud. The animal has ideal protection against the elements."

Speaking of the animals, there's a video of them cavorting on the windswept tundra. It plays continuously on a flat-screen TV behind the store's counter. And I do mean cavorting. When you're not stroking the material on a cable shawl, you can watch them galloping under the midnight sun, or the males charging each other (the resulting head-on 40 mph collisions accounting for their reduced lifespan—12 to 14 years—compared with female musk ox.) You can even spot a couple of musk ox in a compromising moment, making more sweaters.

Mr. Alvarez informed me that the following day he was on his way to the Arctic Circle to meet with his suppliers. He said he signed a deal with them 16 years ago, soon after his first encounter with the fiber at the University of Saskatchewan, to buy everything the native organizations produced. "One of the reasons this business has evolved," he said, "is that I was appreciative of native cultures; this goes back to Peru."

He was going to stop briefly at home in Banff to visit his wife and daughter, then board a plane for Yellowknife in the Northwest Territory—his wife, he said, taking a rain check on joining him in the 50-degrees-below-zero temperatures and at the hotel where he stays with its caribou-heavy menu. From there he'll take another plane to Victoria Island, in the archipelago of Canadian islands north of the Arctic Circle. "I spend three to four days, depending on whether I get to meet all the leaders," he explained. "I have to make the time to wait for them. They live in isolated places."

Qiviuk comes from musk ox, above. Getty Images

Mr. Alvarez conceded that musk ox, which resemble extremely well-insulated bison, "can be dangerous," not that he's encountered any problems with them. "In the wild, it's such a vast region they feel you're so minimal you're really not a threat to them," he said. "I guess if you looked like a wolf that would be a different story."

Indeed, a greater threat to his survival seems to be the lack of shoppers visiting the Plaza's underground Retail Collection. "The traffic hasn't been that great," he conceded. "Even though we're steps away from a lot of people, they still have to make their way down here."