New Zealand author Eleanor Catton has, at the age of 28, become the youngest ever winner of the £50,000 Man Booker Prize for her novel The Luminaries.
Her 832-page tale of the 19th-century goldfields is also the longest work to win in the prize's 45-year history.
"It's a dazzling work. It's a luminous work. It is vast without being sprawling," said Robert Macfarlane, chair of the judges.
Catton was announced as the winner on Tuesday night at London's Guildhall.
When her name was called out, "it almost seemed like the rest of the room ceased to exist," she told the BBC's World Update.
Her book, a Victorian mystery tale set during the New Zealand gold rush, is intricately structured according to astrological charts - with each section exactly half the length of its predecessor.
When it was shortlisted last month, the judges described it as a "Kiwi Twin Peaks".
"You begin it and you think you are in the clutches of a big baggy monster," said Macfarlane on Tuesday, adding that what followed was an "accelerating, quickening tilt to the narrative".
"We have returned to it three times now and we have dug into it - to use its own metaphors - and the yield it has offered at each new reading has been extraordinary," he said.
The prize, announced live on the BBC News Channel, was presented this year by the Duchess of Cornwall.
On receiving the award, Catton admitted that her lengthy, complex novel had been "a publisher's nightmare", saying she had been compelled to buy a bigger handbag to carry it around.
She then thanked her publishers for striking the "elegant balance between making art and making money".
The other authors on the shortlist were NoViolet Bulawayo, for We Need New Names; Jim Crace, for Harvest; Jhumpa Lahiri, for The Lowland; Ruth Ozeki, for A Tale for the Time Being; and Colm Toibin, for The Testament of Mary.
Crace had been the bookies' favourite to win, with Catton reported to have a late surge of support over the weekend.
Macfarlane said the judges' final decision had been made after "just under two hours of pretty tough discussion".
Canadian-born Catton was raised in New Zealand and is the second writer from that country to win the prize. The first was Keri Hulme in 1985 with The Bone People - her first and only novel.
The Luminaries is the longest ever Booker winner, beating Hilary Mantel's 672-page Wolf Hall which won in 2009.
Macfarlane joked: "Those of us who didn't read it on e-readers enjoyed a full upper-body work-out."
Set in 1866, The Luminaries begins with Walter Moody arriving to make his fortune on the New Zealand goldfields. He stumbles across a tense gathering of 12 local men, who have met in secret to discuss a series of unsolved crimes.
Moody is then drawn into a mystery involving a missing wealthy man, a prostitute who has tried to end her life, and an enormous fortune which has been discovered in the home of a luckless drunk.
Catton began writing the novel at the age of 25 and completed it when she was 27. She turned 28 last month.
The previous youngest winner was Ben Okri, who was 32 when he won for The Famished Road in 1991. Kiran Desai was previously the youngest woman to win, at 35, with The Inheritance of Loss in 2006.
"One can approach this as a murder mystery with seances, corpses, lawsuits and puzzles," said Macfarlane.
"It does require investment… but it operates like the best kind of goldmine. You pan and then the yields are huge."
Jonathan Ruppin, web editor for Foyles, said: "For those who are simply looking for a great story, the murder mystery at the heart of the book is thoroughly gripping and that alone should ensure very strong sales.
"But there is so much more to it: a vivid cast of characters who leap from the page, a joyful celebration of language and some remarkable experiments with the underlying process of novel writing; critics who have dismissed it as a pastiche of 19th-century fiction have scarcely scratched the surface.
"Catton is a writer of rare insight and intelligence, who is at the vanguard of the evolution of the novel.
"I'm confident that she is destined to be one of the most important and influential writers of her generation."
The six shortlisted writers each win £2,500 and are presented with a hand-bound edition of their book. As winner, Catton receives a further £50,000.
This year marks the 45th year of the prize, which was won last year by Hilary Mantel for Bring Up the Bodies, the sequel to Wolf Hall.
Next year the Man Booker Prize will be open to authors writing in English from all corners of the globe. It is currently awarded to English-language authors from the Commonwealth, including the UK, Ireland and Zimbabwe.
The decision has split the literary establishment, with critics saying that American novelists will come to dominate the prize.