The first time I meet Lily King, it's early February and snow is falling on the streets of Portland, Maine, in the United States. It's warm in the Speckled Axe café, where a few bearded hipsters are staring into their laptops.

Despite the four foot-high snow drifts outside, when King walks in she's a vision of tropical sunlight: dressed in a multicoloured jumper with an orange scarf around her neck. Her eyes are so blue they pull you in like the tide.

We're meeting to discuss Euphoria, King's fourth book, which was inspired by the life of infamous American anthropologist Margaret Mead. King wants to ask if I will be her assistant, helping to manage her online platforms when she embarks on a book tour in June. Since moving to the US from Hong Kong, where I worked as an arts writer, I've stumbled upon this role of helping illustrious authors manage their online lives.

Lying two hours north of Boston, Maine, with its endless silent forests, mystical inlets and rugged coastline, is a haven for reclusive artists and writers. New York is a 50-minute plane ride away and everyone from Stephen King and Richard Russo to poet Richard Blanco lives in these parts.

I've done my research and know that Lily King has literary clout. Her first novel, The Pleasing Hour (1999), about an American au pair in France, won the Whiting Writers' Award and the Barnes & Noble Discover Award. When Jacqueline Carey reviewed the book for The New York Times, there was a hint of what was to come with Euphoria: "Most writers are good at depicting either intricate social ambiguities or more primitive urges. King proves herself equally adept at both - even as she skilfully demonstrates that the two never exist comfortably side by side."

King's next two novels, The English Teacher and Father of the Rain, are both set in New England and earned her critical success, with the latter winning the New England Book Award.

Born in Manchester, Massachusetts, and now a resident of Yarmouth, in Maine, King and her writing are steeped in East Coast life. But with Euphoria, she is stepping out of her comfort zone and taking on 1930s New Guinea. She shows me the novel's cover design on her laptop: streaks of orange, blue and green that perfectly match her outfit.

"It's from the rainbow gum tree in New Guinea," she says.

The island of New Guinea lies in the southwest Pacific, in the warm waters north of Australia. It's the second-largest island in the world after Greenland and is today divided into Papua New Guinea on the eastern side, and the Indonesian provinces of Papua and West Papua on the west.

Since the 16th century, the island has been fought over by colonists from the Netherlands, Portugal and Britain looking to secure its rich deposits of oil, copper and gold. It has also offered fertile grounds to anthropologists. Tribes have existed here for more than 40,000 years and, because of its towering mountains, endlessly snaking rivers and lack of infrastructure, a rich diversity of languages and tribal customs abound.

New Guinea was a frontier for Western anthropology in the early part of the 20th century. As King writes in Euphoria, "Anthropology at that time was in transition, moving from the study of men dead and gone to the study of living people, and slowly letting go of the rigid belief that the natural and inevitable culmination of every society is the Western model."

Mead and her second husband, Reo Fortune, were here in the late 20s studying the Manus people in the Admiralty Islands. From 1931 to 1933, they were stationed up the Sepik River, in the northeastern edge of the territory under Australian rule.

It was Mead's book Coming of Age in Samoa (1928) that thrust her into the spotlight and established her as the world's most famous anthropologist. In the book, she described her studies of young people on the island of Ta'u, in the Samoan Islands. Her graphic accounts of adolescent sexuality made Mead an overnight sensation. Her next book, Growing Up in New Guinea (1930), focused on the Manus while Sex and Temperament in Three Primitive Societies (1935), which became a key force behind the feminist movement in the US, is the work King draws on in her novel.

A towering figure in history, Mead served as president of the American Anthropological Association and curator emeritus of ethnology at the American Museum of Natural History, and wrote and edited more than a dozen books before her death in 1978 at the age of 76.

But what was Margaret Mead like as a human being? And will King be able to pull off this fictional reimagining of her?

WHEN WE MEET FOR the second time, it's late June and the answer appears to be yes. The New York Times Book Review has published a full-page cover review, calling Euphoria "a meticulously researched homage to Mead's restless mind and a considered portrait of Western anthropology in its primitivist heyday". Amazon has named it a "best book of the year so far" and the film rights have just been sold to British director Michael Apted, whose credits include the 1988 movie Gorillas in the Mist.

Critics agree that King has done something quite uncanny with Euphoria. She has managed to whip Mead off the dusty shelves of history and place her tantalisingly in the present.

As we meet in Portland's Old Port, I'm keen to peer into King's mind to find out why she wanted to write about Mead.

She says her curiosity began nine years ago, in 2005, when a friend took her to a bookstore closing near the Old Port.

"I felt like I had to buy something, so I picked up a biography of Margaret Mead by Jane Howard," she says.

Not far into the book, King came across a chapter titled "The Closest I've Ever Come to Madness".

It was the end of 1932, and Mead and Fortune were in New Guinea when they ran into Gregory Bateson, a British anthropologist (and soon to be Mead's third husband). The three instantly connected and Bateson invited the couple to remain in the region instead of continuing on to Australia. He found a tribe for them to study and, in the months that followed, the three fell into a dramatic love triangle. Mead was 31 and the men in their late 20s.

"I got to this and thought, 'Oh, that would make such a good novel,'" says King, her eyes gleaming. "And then Father of the Rain became such a difficult book to write, it was so emotional and I did have to take long breaks, so I would start doing a little reading about Margaret Mead … then I started taking notes. The minute I started taking notes, I started getting ideas for the novel."

Euphoria's protagonist, Nell Stone, follows a similar trajectory to Mead. She has just had a book published and her husband, Fen, has the stench of jealousy about him. The novel opens with Nell and Fen sitting in a canoe on the Sepik River, covered in cuts and sores, their eyes feverish with malaria, as they leave behind the tribe they have been studying for the past 18 months. Someone throws something at them. It bobs a few yards from the stern of the canoe.

"Another dead baby," Fen says.

With her glasses broken, Nell didn't know if he was joking.

They board a motorboat and join a group of Australian couples at a Christmas party. King nails the colonial tone - the Aussies are overdressed for the tropical heat and it could just as easily be a scene from a Royal Hong Kong Yacht Club ferry several decades ago. The boat takes them upriver to a club where the pair meets English anthropologist Andrew Bankson. Like Bateson, Bankson comes from a prominent but tragedy-prone British family and just three days earlier had attempted to drown himself in the river.

King's original plan was to stay true to the facts but then the novelist in her kicked in.

"The characters took over and the minute I started writing the dialogue and getting into their heads, I left these people far behind," King says.

She quickly corrects herself, adding, "I shouldn't say far behind. I took so much, as much as I wanted to take I took, but by the end they really are on a very different journey."

As Joan Frank, of the San Francisco Chronicle, writes in her review of Euphoria, "King's superb coup is to have imagined a story loosely founded on the intertwined lives of the above three that instantly becomes its own, thrilling saga - while provoking a detective's curiosity about its sources. That saga's star is young Elinor 'Nell' Stone … Mead's rough stand-in - except that Nell's not quite what many may conjure [rightly or wrongly] when they think of a young Mead - that is, as a big, doughy, dotty brainbox, perhaps kin, in warbles and wattles, to Eleanor Roosevelt or Julia Child."

At first, King says, she struggled with accessing Nell's character. It was only when she switched the narrative voice to Bateson's perspective that the full energy of the novel was unleashed.

"Her persona is sort of fixed in history," she says of Mead. "It's like this monolithic thing that is not nuanced. I think I was really blocked by that. But I also found in her memoir, when I was trying to find her voice, that it was very hard to find. It very much felt like she was writing for posterity. It didn't feel raw and authentic. It felt very polished and the rough edges were smoothed over."

In her lush prose, King delivers a gripping love story alongside an astute portrait of anthropology in the 30s. Through the prism of the three interlocking characters, each of whom are struggling to discover tribal secrets while coping with their baffling feelings for each other, she shows just how subjective it all was. Fen serves as an excellent critical device in the novel; his conclusions are not the same as those of his wife yet they are supposedly witnessing the same things.

At the start of the novel, King includes a quote by Ruth Benedict, Mead's mentor and lover: "Experience, contrary to common belief, is mostly imagination."

Which perhaps explains how King wrote a novel based in New Guinea without ever having set foot on the island: she imagined the entire book from her attic in Maine.

When I bring this up, she says, "I don't even like going to Boston for the night and being away from my family." She also points out that the island is not the safest place to visit these days. "I read all sorts of accounts about New Guinea - from that time, before that time and contemporary," she explains. "But also, I took all of that information and used 0.01 per cent of it.

"I do not like an overresearched book; I do not want someone's research in my novel. I want the story."

AS READERS DEVOUR THE story this summer, the life of Margaret Mead will once again be in the spotlight.

When asked why Mead was so important, King says, "It seemed that her interest in anthropology was to promote social change in America. And that's a very political thing for an anthropologist to be doing; you are supposed to be objective. So much of what she was writing, attitudes towards women, childrearing, the family … she thought the small, claustrophobic, narrow-minded American family was extremely oppressive and dangerous to the rearing of children."

In Euphoria, King also paints a picture of tribal societies. As the plot moves towards a heady, euphoric climax, she illustrates how anthropologists work with these communities, by relying on their own "informants" to help them unlock the culture.

"I think it's an incredible word," she says. "You want an informant who has an ability to look from a distance at his or her own tribe. Anthropologists are always trying to find the misfits to talk about what the tribe is like. Because if you're in the tribe, then you don't really know; they can't talk about it as well."

This misfit quality, being an outsider, lends itself rather well to the writing life. Many authors sit at their desks, separated from their communities. They are the misfits of society; the ones on the edge who are able to look back and see clearly.

This is what King has appeared to have pulled off in Euphoria. Without being an anthropologist, an expert on New Guinea or Margaret Mead, she has nonetheless come extremely close to capturing the spirit of the world's most famous anthropologist.

Perhaps Benedict was right: neither history nor experience are a list of facts in a book, but the imagined images that flow through our collective minds.