ASK LUCY IRVINE to name three things she'd bring to a desert island, and she screws up her face and wrinkles her nose and stares out with those huge, heavily mascaraed blue lagoons. The complete works of Jane Austen? The best of the Beatles? Fourteen cases of Cha teau Lafite? Preferably twist-top?

"A willing self," she proclaims. "And a very strong love for life." She pauses. "And a sense of humor."

Irvine ought to know. She spent a year on a desert island and lived to write about it in "Castaway," her deliciously ribald and critically acclaimed account of forsaking civilization for a tiny stretch of sand off the coast of Australia called "Tuin" with an adventure-seeking stranger, a man twice her age whom she neither loved nor trusted but was forced to marry by Australian immigration authorities for the sake of the project.

(They have since separated, and Irvine says he refuses to give her a divorce.)

The book's subtitle is "a story of survival," and the physical dangers (starvation, dehydration, poisonous snakes, sharks, deadly coral and infected sores) seem slight compared with the psychological ordeal the 28-year-old Irvine endured.

Forget "Swiss Family Robinson." Forget "Swept Away." This is Edward Albee's version of "Gilligan's Island."

"It's not an escape. When you get a man and a woman and a piece of land, you have all the problems in microcosm of humanity. Sex. Violence. Politics," she says. "It brought far more to me, painwise and joywise, than I'd anticipated. It was a magnificent, frightening experience."

She is sitting on a lush square of grass near her Washington hotel, shaded by a large boxwood. "I'd love to take my clothes off," she says, waving her arms and tugging at the voluminous pale green material shrouding her ample figure. "I can't sit in the sun with this stupid dress on. I only want to be in the sun naked."

Her sun-bleached hair is pulled into a fat topknot, camouflaging several bald spots (souvenirs of island malnutrition), and her skin is a creamy palette of pancake makeup, highlighted by a swab of lip gloss over a full mouth. She speaks freely and rapidly, her laugh is deep and robust, and the whole image is Lynn Redgrave on speed.

"I laugh far more easily than I ever did. I don't take things seriously anymore."

A blithe spirit from Scotland who left school at the age of 13, Irvine--a sometime waitress, model, pastry cook and concierge--spotted a small ad in a London newspaper three years ago: "Writer seeks 'wife' for year on tropical island." It was placed by a craggy, world-weary Englishman named Gerald Kingsland who planned to write a book on the experience. Kingsland, who had already lived on several islands, found in Irvine the female partner he wanted: docile, dependent and unfailingly cheerful. And while Kingsland was not exactly her type, "I would have gone with anyone who wasn't a pathological maniac," she laughs.

Irvine, however, quickly sensed their cross-purposes. She was looking for an island. He was looking for a woman.

"When I first met Gerald, I was very well aware that he was giving me the same spiel that he'd given to a lot of other women . . . I was intrigued by him and by my reactions to him. He was not the sort of man I'd ever gone out with."

They arranged to spend the year on Tuin, and after some false starts, arrived on the island with meager provisions and hopes to raise their own crops. The Australian government, which owns Tuin, had insisted they marry, which Irvine deeply resented. By the time they got to the island, they were emotionally and sexually estranged, with Kingsland prepared to be the dominant partner, while Irvine tiptoed through the mangoes.

"I really believed that Gerald was going to be the one to run the show, and I was quite prepared for that."

But Kingsland, deprived of his health and sexual companionship, began to deteriorate, as she tells it. Bites from sandflies festered, leaving him virtually unable to walk. His flagging physical energy coincided with a deflated spirit, leaving his female companion to fend for both of them.

"At first, I didn't enjoy it. It was a matter of my respect for Gerald decreasing with every day that I found I was stronger. After a while, I began to receive such pleasure through the discovery of my own strength that he, to a large extent, became rather irrelevant to my experience on the island."

While Irvine chopped the wood for the fire, climbed coconut trees, speared sharks and other fish, plucked passion fruit and explored the vast and potentially dangerous interior of the island, Kingsland, described by Irvine as a "poor whining man with bad legs," grew more and more verbally abusive, refusing to leave the campsite.

They lost all track of time, buffeted by the winds and parched by the sun. Their garden shriveled for lack of water, their provisions dwindled to a few cups of rice, and both suffered from an array of maladies. Finally, they were discovered by natives from the nearby island of Badu, who showed them where to find fresh water and fashioned a small boat for them. Buoyed by the islanders' gifts of rice, flour and fresh milk to complement the castaway diet of fresh and dried fish, Irvine softened her resistance to Kingsland's constant sexual overtures by inventing an alter ego, "Millie," who was everything Irvine was not.

In a grotesque pantomime of a "fallen woman," she rouged her cheeks and lips. It was, after all, a matter of survival.

"I think I made her so different because it made her more out-of-body. Luring Gerald into the shelter, she didn't sully anything, although she was certainly sullying myself quite thoroughly."

Their relationship improved, despite the night Irvine sat on Kingsland's dentures, shrieking with alarm at what she thought was a deadly, razor-fanged lizard of some kind. "Gerald's teeth gave me the biggest shock," she says. "If you knew how frightened I was. Imagine something with those big horns on it. It was absolutely wicked."

Although Kingsland wanted to leave Tuin before the year was up, Irvine felt committed to the project and engaged "Millie" to keep him there.

In June 1982--12 months after she landed on Tuin--Irvine finally left Kingsland, who has by now become a small-engine mechanic much in demand by the islanders of Badu who welcome him as a permanent castaway. Irvine flew to Sydney, frightened, excited and "delighted to be in the soft textures of civilization."

"The scent that people wore affected me in a very heady way. And that was beautiful. The cars affected me strongly. Hearing a piece of music that I was familiar with stirred all sorts of old chords in me I hadn't felt. Beauty came to me very strongly, and ugliness as well. I was so childlike. Things pleased me so much, like walking on a carpet which didn't cut you and you didn't have to look out for stones or coral."

Still, she says, her identity as a woman was shattered by her performances as "Millie." "I seriously thought of becoming a prostitute. I didn't know what else to do. My personality as a woman was almost totally disintegrated, because having been called a ---- for that length of time, that's all I felt I was."

"I didn't think I was ever going to enjoy sex again. The discovery that I could was fantastic. That released me immediately from all thoughts that I could ever be a prostitute because I could never possibly use that very beautiful thing as a commodity.

"I took off from there and temporarily was slightly promiscuous. It didn't suit me. I find it difficult to find men who will accept a woman who gets up in the middle of the night and goes home. They tend to think, despite all they say, that they must be the ones to get up and go."

There are other changes in her life. "I can't watch television. I get bored with it. I never experienced boredom on the island. Loneliness has come to me, since being in a crowd again." Friends were perplexed. "I went away as ordinary Lucy and came back as Lucy-who'd-been-on-a-desert-island-for-a-year. They reacted to me as if I were a Martian. And I felt like a Martian."

Back in England, Kingsland's publishers approached Irvine to do a book. "What they were actually trying to do was recoup their losses on Gerald because they had advanced him quite a considerable sum years before. I thought I would have a go. I started writing the true story of what happened and the publisher was horrified, because the synopsis he had given them years before was a sort of lovely blue lagoon, coffee-table book. I headed straight into the rude bits and four-letter words."

They asked her to work with another journalist to make the story more "sympathetic. I said, 'This is my life. It's not fiction. If you don't like it, stuff it.' "

The publishers relented, and Irvine finished the manuscript. She flew to Australia to show Kingsland the book, and to return to Tuin for a brief visit.

"We had our one and only civilized meal together, isolated in a restaurant in Sydney, not any longer on an island surrounded by sea, but on a table. Really like an island, surrounded by people. He had read the book but evidently only skimmed it because after the first glass of wine it was absolutely the same thing all over again. 'Will you be "Millie" again. Just one last time?' "

Kingsland even offered her $100, she says, but she left the restaurant, consumed with anger. "Sex gets in the way of everything," she sighs. She has not seen him since, but has learned that he plans to write his own book. He refuses to grant her a divorce.

"It's the only power he has left over me, and it's probably more financially beneficial for him to stay married to me. To really dig the dirt, I have had one letter from his solicitors saying, 'We don't think we can advise Mr. Kingsland to consent to a divorce until you have made a lump sum settlement.' Which is," she sputters, "straightforward bribery."

Did she ever love him?

"I did. But never as a man. Never with desire. As a co-survivor. As somebody I formed a bond with because we went through these things together. Tuin brought us together. If there hadn't been an island, there wouldn't have been a Gerald and a Lucy, and when the year came to an end, there was no longer a Gerald and Lucy. In a way, people will look upon this as cold, but it doesn't seem cold to me."

Her year on the desert island "cost me a lot, but it gave me more. For a while," she says quietly, "I thought it was the other way around."

The urban sun is descending and the sidewalk traffic picks up. A bus sounds its horn and a plane roars overhead. A small gray-and-white bird lights on a branch of the boxwood, whistles and flies away.

Irvine whistles back.