Sometime between now and Christmas, the National Gallery's curator of modern prints and drawings will have to travel to Kansas City, Mo., sit face-to-face with one of the richest men in America and explain why 28 watercolors attributed to American icon Georgia O'Keeffe, for which he paid $5.5 million six years ago, are now worth squat. At least as far as the National Gallery is concerned.

But that's the easy part. It was curator Ruth Fine--along with two of her bosses, National Gallery directors J. Carter Brown and Rusty Powell--who urged banking billionaire R. Crosby Kemper to buy O'Keeffe's so-called "Canyon Suite" in the first place. As Kemper will surely remind her when they meet.

Discovered in a garage in the late '80s by the family of an early O'Keeffe boyfriend, they'd been purchased for around $1 million by Santa Fe-based megadealer Gerald Peters. Since the works, though undocumented, were similar to the artist's early work and had been authenticated--verbally, but not in writing--by O'Keeffe's longtime assistant, Juan Hamilton, Peters packaged and promoted them as rare early O'Keeffe watercolors, made while she was teaching art at West Texas State Normal College in Canyon, Tex., between 1916 and 1918, her breakthrough years. Every known O'Keeffe scholar agreed that they were her work, and several wrote catalogue essays and offered sound bites for television news and documentaries.

Peters dubbed them the "Canyon Suite," gave each one a title, held an exhibition and published a catalogue with a 20-page analysis by former National Museum of American Art director Charles C. Eldredge, now a Hall distinguished professor at the University of Kansas. The National Gallery kept them in its vaults for two years while curators scrutinized them and sought a donor. It was then that curator Fine and other gallery officials began wooing Kemper, urging him not only to buy what they called this "national treasure" but to do the patriotic thing and give it to the National Gallery. They even offered to carve his name into a marble wall of the West Building.

Kemper finally bought the "Canyon Suite" from Peters but decided to keep it for his own Kemper Museum of Contemporary Art, which opened in Kansas City in 1994. It was still a featured attraction there last month when Kemper received a shocking letter from Fine informing him that the National Gallery and the Georgia O'Keeffe Foundation, its partner and partial funder in this endeavor, had just published the definitive catalogue raisonne listing all of O'Keeffe's accepted works, and that "Canyon Suite"--along with 220 other rejects--hadn't made the cut.

Kemper blew his stack, called out his lawyers, hired his own paper conservator and told the Wall Street Journal that the National Gallery had "declared his watercolors fake" out of spite because he had kept them for himself. Fine calls that charge "absurd." "We never called them fake," she says. But they might as well have. As far as the art market is concerned, "Canyon Suite" is now an albatross.

The gallery's reasons were "frustratingly vague," according to Kemper Museum Director Dan Keegan. "They refused to tell us any details by phone, saying only that there were problems with some of the paper and some stylistic problems." To quell the furor, project director Fine, her paper conservator, Judith C. Walsh, and catalogue author Barbara Buhler Lynes offered to meet with Kemper and present their case. But Kemper put them off, hoping he'd get better news from his expert, which, unfortunately, he did not.

"It's a public hanging without a trial," complained one of many Santa Fe dealers who've been touched in a negative way by the publication of this catalogue. Altogether, about 250 works were turned down--including one now in the Georgia O'Keeffe Museum in Santa Fe.

Meanwhile, a red-faced Peters, who has offered to return Kemper's money, couldn't even get his phone calls satisfactorily returned by the National Gallery. "I'll take the watercolors back if someone will tell me what the problem is," the dealer says.

By yesterday, a potentially explosive chain of events was in motion: Kemper, who's received mostly bad news from his paper expert, has agreed to hear what the gallery's experts have to say when they come to Kansas City this month. But he's also made clear that he may simply wash his hands of the whole matter and unload the works on Peters. Peters, meanwhile, speaking from his New York gallery, said, "I'm up a creek here. I've talked to the FBI. . . . They've got a great lab there--maybe they can figure it out."

The big mystery now is what caused Fine, who is widely respected, to change her mind so dramatically. "It took many years before I went over to the other side," she said in an interview late last week. "It was not one thing. But there was a moment when I stopped going back and forth. And it was late, after a lot of torment." But she wouldn't explain what had convinced her.

It now appears that the first serious questions were raised by gallery paper conservator Walsh, who's been detailed to the project for several years and has looked at 1,000 O'Keeffe works on paper. It was Walsh who discovered that at least three landscapes in the Kemper group were painted on paper that wasn't even produced until the 1930s. That blew the 1916-18 dating of Peters's "Canyon Suite" out of the water for those three objects, but not for the rest. But "when one thing isn't right, usually something else isn't right," Fine said.

Stylistically, too, there were problems, though Fine was at pains to explain them while remaining within the project's bounds of confidentiality. "Just look at them, and compare them with accepted watercolors in the catalogue raisonne," she pleaded. But hadn't she been looking at them all along? Wasn't it old-fashioned eyeball "connoisseurship" that got Kemper into this multimillion-dollar pickle in the first place?

All of this, in the end, leads back to the question of provenance, the origins of this group of works, which were unknown until the year after O'Keeffe's death in 1986. Fine made clear that anything that emerged after 1986 and had no documentation from before that year was inherently suspect. And until last night, no one directly involved with the sale was talking.

In 1987, Peters bought the watercolors from Terry Caballero, a therapist from the Texas Panhandle. She is the granddaughter of Ted Reid, the friend and fellow nature-lover whom the 30-year-old O'Keeffe met while teaching in Canyon.

And in a telephone interview last night, Caballero said, "I never said they were Georgia O'Keeffes. I've got in my contract with Gerald Peters that he would buy them if Juan Hamilton would authenticate them, and Juan did." Hamilton did not return a call to his home in Hawaii last weekend and was said to be traveling.

The tale of the Reid-O'Keeffe friendship is a romantic one, perhaps embellished by time: Reid had a car, and the two often drove to the countryside, where she made many watercolors and drawings of the canyons and the sunsets. Against her advice, Reid went off to the Air Force in World War I, and upon his return married one of O'Keeffe's students. They stayed in touch, on and off, for the rest of their lives. When her husband, Alfred Stieglitz, died, she wrote to him. When Reid died, one of his daughters wrote to say he'd been buried that day.

The only known document explaining the source of the works, dated 1988, was written by octogenarian Emilio Caballero, a retired art teacher in west Texas. He wrote that he'd received a package from his old friend Ted Reid in the '70s, when Caballero was in the midst of moving to a new office at West Texas State. He said he stashed boxes of things, among them the envelope from Reid, in a locker in his garage, where it remained for 12 years, until he moved to a new house. And when he found it, he gave it to Ted's grandchild, who had become his daughter-in-law.

Peters admitted Wednesday that the rest of the story he attached to these watercolors--how O'Keeffe gave them to Reid when he went off to war, etc.--was his own invention. "It was just guesswork," he said. "The Caballeros didn't say anything about that.

"They've thrown out the baby with the bath water," Peters said of Fine and the others who worked on the catalogue raisonne. Until all the facts are known, others might say that he sank the lot with salesmanship and packaging that were too clever by half.