London author Stef Penney has won the Costa Book of the Year award for her debut novel, the Tenderness of Wolves.
Stef Penney researched her book by using the British Library
The book is set in Canada - a country the author has never visited because she had agoraphobia.
The award - formerly the Whitbread Prize - pits five winners of separate categories against each other for the Book of the Year.
Penney, aged 37 and a screenwriter, won the "first book" award before scooping the top £25,000 prize.
Of the other short-listed authors, William Boyd had won best novel for his spy story Restless, while Brian Thompson's Keeping Mum had taken the biography prize.
John Haynes won the poetry prize, and best children's book went to Linda Newbery for Set in Stone.
After her name was read out, a shocked Penney said: "I'm still shaking. I'm supposed to be a writer but I don't know how to describe how I feel."
Penney's book follows a 19th Century couple who leave Scotland as part of the Highland Clearances and emigrate to a remote part of Canada.
The author relied on research carried out at the British Library.
She said: "Just because you go somewhere it doesn't mean that you have a peculiar or vivid or insightful take on the place.
"Every story takes place in the landscape of the imagination.
"Regarding this wide, open landscape which I find quite alarming, maybe it's even more vivid because I couldn't go and look at it and see how mundane it really is."
Penney, who now has her fear of open spaces under control, said of her agoraphobia: "It's not a distant memory. I don't think it ever goes away completely. I can fly but it's still a bit of a big deal when I'm travelling."
She added that she had started writing a second book - this time set in Britain.
Armando Iannucci, the chairman of the judges, said Penney's work was an "extraordinary first novel".
He described it as testament "to the power of good writing" and said: "Within about 50 pages I was completely in love with it."
A total of 580 books were submitted for the prize, which was won last year by Hilary Spurling for her biography Matisse the Master.
It is the fourth time that a debut novel has won Book of the Year, since its inception in 1985.