A gripping account of a doomed attempt to climb Mount Everest has won Britain's leading nonfiction book prize.
Into the Silence: The Great War, Mallory and the Conquest of Everest by Canadian author Wade Davis was awarded the 20,000 pound (NZ$38,830) Samuel Johnson Prize on Monday.
British mountaineer Mallory - the man who famously declared he wanted to climb Everest "because it is there" - died on the world's highest peak in 1924, and debate still rages about whether he reached the summit.
Davis sets the expedition in the context of Britain's imperial history and the trauma of World War I.
David Willetts, a British Conservative lawmaker who chaired the judging panel, said the book is "an exciting story of human endeavour imbued with deep historical significance."
"This fascinating historical narrative of a great adventure manages to shed new light on events and stories we thought we already knew," Willetts said.
Davis beat five other shortlisted titles, including Katherine Boo's Behind The Beautiful Forevers: Life, Death and Hope in a Mumbai Slum and Steven Pinker's The Better Angels Of Our Nature: A History Of Violence and Humanity.
The prize recognizes English-language books from any country in the areas of current affairs, history, politics, science, sport, travel, biography, autobiography and the arts.
Davis, the National Geographic Society's explorer-in-residence, has written 15 books on topics ranging from Haitian zombies to the Amazon rainforest.