In this day and age, not even Hollywood would believe the scenario: the bright, coltish daughter of an ambitious American millionaire stealing the heart of a strife-weary Arab king 16 years older than she. But on June 15, if tradition holds, a celebratory clamor of Arab Legion bagpipes, goatskin war drums and old Bedouin saber dances will herald just such a match for just such a king and his princess.

The wedding in Raghdan Palace overlooking Amman will be the fourth for Jordan's King Hussein, 42, and his second to a foreigner. But for his new bride, Elizabeth Halaby, 26, who is Washington-born, prep school bred and decidedly casual by inclination and habit, the event will mark a personal passage almost beyond imagining. Already, by Jordanian custom, she is converting to Islam and taking an Arabic name ("Nur el Hussein," which means "Light of Hussein"). With the aid of a tutor, she has begun a wholesale readjustment to life in a country and a station light-years removed from her own. The daughter of former Pan Am president Najeeb Halaby, whose father was an Arab immigrant, she is by inheritance fractionally Syrian, but the point is academic: Her background and style are all-American, from her taste for blue jeans and minimal makeup to her blond good looks and outspoken liveliness. A curious mix of '60s rebel and '70s career woman, she is, in the words of her Princeton boyfriend, Raymond "Pat" Patterson III, "the last woman of a passing era and the first woman of a new one." Her future life as a princess of the Hashemite dynasty may severely test the mettle of both.

Lisa's background carries only an occasional hint of such a sea change. Fifteen years ago, when Hussein had been king 10 years, she was a tomboyish sixth-grader at Washington's elite National Cathedral School—sneaking cigarettes in the washroom, playing a mean game of field hockey and wondering what her classmates were beginning to see in the boys at St. Albans. "She wasn't attractive," says a friend, who remembers a tall, gawky girl with big glasses. "And she was never in the most popular clique. But she had a mind of her own and was respected for her intelligence." She and some of her friends—among them Grace Vance, daughter of Cyrus, and Carinthia West, now a model and once a girlfriend of Mick Jagger—worked in LBJ's 1964 campaign. The night of the election they held a slumber party at West's house. "That was strictly against school rules," recalls co-conspirator Carrie Rowan, who now runs a Washington boutique. "Next day the headmistress called us on the carpet and telephoned all our parents. But Lisa stood right up to her and told her the election had meant a lot to us. She always was one of the girls who spoke her mind."

The next year, when Jeeb Halaby resigned as head of the Federal Aviation Administration to join Pan Am in New York, Lisa transferred to the Chapin School in Manhattan. Two years later she enrolled at the equally exclusive Concord Academy in Massachusetts. With her father's rising fortunes (he was named Pan Am's president in 1968) came summers in southern France and Greece, winter vacations in Palm Beach and Aspen, and an abiding love of travel, tennis, sailing and skiing. At Concord she played varsity hockey, basketball and lacrosse, worked on the school paper and yearbook, joined the debating club—and learned to court adventure. "I went to Greece with her at 15," recalls schoolmate Mary Sherman. "She was different from most of the boarding school types, and I felt very alive when I was with her. You could always depend on her to do something interesting."

Entering Princeton in the fall of 1969 with the historic first coed class, she became a symbol of the change on campus as one of the university's first female cheerleaders. "We said we'd only do it if we didn't have to wear those funny little skirts and bobby sox," her friend Podie Lynch remembers. "She and I wore sailor pants instead. But after about four games Lisa and I decided it was ridiculous and dropped out. We felt dumb." Lisa may have been among the most attractive of the freshman sisters ("the one we really freaked out over," as one male classmate puts it), but her taste in men inclined to "different guys," Lynch remembers, "never middle-of-the-road types. She was nontraditional, never the preppie image—certainly not the kid you'd expect to end up marrying a king."

In the middle of her sophomore year, Lisa decided to leave Princeton for Aspen. There for a year she skied, took photography classes and waitressed at the chic Jerome Bar. "That's what was neat about her," says Princeton friend Tom Croonquist. "She didn't have to work—she could've just taken financial help from her family." That summer she fell in with peace activists who drifted in and out of a big Victorian house rented by political prankster Dick Tuck. Lisa often slept over in a spare room and, as Tuck remembers it, "guys lined up outside our house at 7 in the morning to ski with her. She was a lovely girl."

The following year Lisa returned to Princeton with a fresh commitment to academe. Plunging into her studies in the School of Architecture and Urban Planning, she spent much of her time at her studio desk, which she surrounded with greenery. "She was more determined than most of the females at Princeton," recalls another architecture major, Hallett Johnson. "I wouldn't say she was a snob, but she had her own little artsy, creative group and was only close to a couple of people." One was Pat Patterson, son of the present general manager of the Houston Rockets basketball team and an avid potter, whose campus costume was a pair of white overalls. Pat and Lisa set up housekeeping in a small, sunny apartment during their senior year and filled the place with his pots and her plants. "She had too much confidence and too much going on to spend time worrying about women's lib," says Croonquist of that time. One dinner party earned her a reputation for "terrific lasagna."

Patterson was hardly the love of her life—"It was more like good friends than an intense romance," says one of their teachers—and after graduation they went their separate ways. He spent two years traveling in Asia before settling down as a sculptor in Venice, Calif.; she went through a succession of jobs in urban design—from Philadelphia to Sydney, Australia to Tehran. "She was attuned to Iran's problems, and seemed to feel no ties to America," recalls Signe Nielsen, her American roommate during an international conference in Tehran in 1975. By then Lisa's father had left Pan Am to become a retailer of Western technology to developing nations. Two years later Lisa took a job with the Royal Jordanian Airline, and began traveling regularly to Amman.

By the time she first met Hussein, at a ceremony last year for the airport her father's company is helping to build in Jordan's capital, she appeared comfortably acclimated to Jordanian life. Hussein, a jet pilot, considers the airport a favorite project, and apparently saw Lisa from time to time.

Several months ago she was invited to lunch at his palace in Aqaba with her father and two of his friends. But, according to former diplomat Marietta Tree, whose architectural firm had employed Lisa in Tehran, she took the young woman to an audience with Hussein in early April and only then did the ice irrevocably melt. "Lisa was reluctant to go," Tree recalls, "but it must have been love at first sight. As we left the king said to Lisa, 'You're a planner and I need some help with problems at the palace. Would you have lunch with me tomorrow?' " By one report, that lunch lasted eight hours.

Lisa's parents, divorced last year, were not surprised by their daughter's engagement. "We knew the romance was blossoming," her mother, Doris, told reporters while traveling to Jordan with Lisa's sister, Alexa, 23. "The only thing that bothers me," she added half in fun, "is that I'd always hoped my grandchildren would be around the corner from me." Brother Christian, 24, a folk musician living in California, caught up with the family in Amman.

Perhaps the Halabys have cause for concern. Lisa, after all, is an innocent when compared to Hussein, who has lived through his grandfather King Abdullah's assassination, his father's mental illness and abdication, numerous attempts on his own life, two divorces and, just last year, the death of his third wife, Queen Alia, in a helicopter crash. Few who know Lisa doubt that she will carry out her royal duties—as honorary chairman of all Jordanian charities, and Hussein's consort at official functions—with uncommon verve and style. But life as a Muslim princess may bring with it unfamiliar proscriptions. Ex-roommate Patterson finds the idea of his Lisa as an Arab princess "ludicrous to think about," and one Princeton instructor commented, "Lisa wasn't a hippie, but she wasn't straight either. She ran with a fairly fast crowd. I can't see her fitting into the rigid Middle Eastern society." One Arab student noted last week: "What Miss Halaby must learn is that here in Jordan women will never be equal to men." That has hardly been the lesson of Lisa Halaby's life thus far; nevertheless, it is one she seems determined to learn. "My career," she said in Amman last week, "is my life with his majesty the king."