The short answer is a single image that has haunted me all my life: a young boy wakes up one morning to a sky so black he cannot see his hand in front of his face.

The boy was my grandfather, the morning was in April, 1875, and the volcano Askja had just erupted in a remote region of northeast Iceland, hurling ash so furiously it obliterated the sun for days. The ashfall covered a vast area - killing off all vegetation and livestock - a final blow for an already impoverished people struggling under colonial oppression. A year later, my grandfather and his family, along with thousands of others, left for Canada, to escape their lives of hardship and join a "New Iceland" settlement on the shores of Lake Winnipeg.

The book's narrator, Freya, spends the summers of her childhood in Gimli, an Icelandic fishing village in Canada, as well as time in Iceland. Were these parts of the book based on your own life experiences?

Actually, I'd never been to either Gimli or Iceland until I started researching the book. And I didn't have any relatives myself growing up, like Freya does - no aunts or uncles, grandparents, cousins. In The Tricking of Freya I invented the extended family I never had, and then lived with them for years, in my imagination. So the book isn't autobiographical in a direct sense.

But indirectly it is. When I was growing up on Long Island, my mother was always telling me stories about the lives of "our people" and her childhood in the West End, Winnipeg's Icelandic enclave. So in that sense, the book is intimately connected with my family history and who I am.

Freya's mother and her aunt Birdie argue about whether Freya, an American girl growing up in Connecticut, should be taught Icelandic or not. In some ways, The Tricking of Freya is a classic story about the cultural conflicts that arise in immigrant families, the tensions between preservation and assimilation.

That's true, and in Freya's case, it becomes further complicated when she experiences a series of tragedies, including the suicide of her beloved aunt Birdie. For Freya, the only way to survive emotionally into adulthood is to turn her back on the past - which also means the Icelandic cultural inheritance her aunt tried so hard to pass on to her.

Often we have to block out personal memories that are painful or traumatic, only to find that later in life we're compelled to revisit them. In Freya's case, coming to terms with the past doesn't just mean things that happened in her own life, but events and traditions going way back in time in Iceland. I'm a firm believer that we're influenced by our ancestors, even the ones we've never heard of.

When Freya grows up, her grandmother wants to pass on to her the "Blue Book," a family genealogy that stretches back to the settlement of Iceland. To many of us, having so much family history at your fingertips seems astonishing.

Icelanders have a cultural obsession with documenting genealogy and family history - perhaps not surprising for an isolated island nation of just 300,000 people. On my first trip to Iceland, a genealogist produced for me a computer printout connecting me back - generation by generation - to the ninth century.

In contrast, many Americans know very little of their family history, sometimes not even where their own grandparents were born. That may be because families moved around and lost track, or in some cases, the family history was obliterated - by the Holocaust, or slavery, or the genocide and displacement of Native peoples. So I feel very privileged to have access to so much family history, which has deeply enriched my sense of self.

How did you go about researching The Tricking of Freya?

Actually, I started researching the book long before I knew I was going to write it. My mother had started sending me all the family documents - letters, photos, memoirs - along with her copies of the sagas, eddas, and histories of Iceland. Soon I was utterly immersed, and eventually I became convinced there had to be a novel in it all.

One day - courtesy of my mother, of course - a huge 800 page book arrived at my house: Icelandic River Saga, by the local historian and genealogist Nelson Gerrard. It was a highly detailed account of all the settlers who had populated "New Iceland" in Canada, including my grandfather's family. I poured through that book for several years, returning to it again and again.

But my research wasn't all through books. I traveled to Winnipeg and Gimli, interviewing old timers, visiting the libraries and the old historic sites. I also made three research trips to Iceland, where I met and stayed with distant relatives who were incredibly welcoming and generous.

What was your most unusual experience in researching the book?

Just visiting Iceland itself is an unusual experience. In the course of my travels, I trekked through lava fields, rode on a snowmobile across a glacier, and took a boat trip on a glacial lagoon.

I think the highpoint was the month I spent as a writer-in-residence at Klaustrið (The Monastery), living alone in a stone farmhouse bequeathed by one of Iceland's most famous writers. It was just downstream from where my grandfather had been raised. I arrived at the beginning of May in the middle of a tremendous blizzard. It was so stormy most of the time I could hardly venture outside without getting blown over. There was nothing to do but write. I got more writing done in that one month than I had in the whole previous year.

How long did it take you to write the book?

It was truly a saga! I wrote the book over a period of about eight years, in several incarnations, with various narrators and points of view. But I can't say I actually spent eight years writing it, because I was working in the software industry much of that time, trying to fit the book in on the side. Finally, I quit my full-time job, cashed out my 401K, and started having larger blocks of time to write. That was a big risk, obviously, and so was the debt I incurred from my three trips to Iceland, but I'd become really driven to finish, whatever the cost.