An account of life in North Korea drawn from interviews with defectors has won the £20,000 BBC Samuel Johnson Prize for non-fiction.
Nothing to Envy, by Los Angeles Times journalist Barbara Demick, beat five other works to the accolade.
Evan Davis, presenter of BBC Radio 4's Today show and chairman of the judges, called the book "gripping and moving".
He said it was "a real testament" to Demick's work "that a book on such a grim topic can be so hard to put down".
This year's winner was announced at a ceremony at the Royal Institute for British Architects (Riba) in London.
Subtitled Real Lives in North Korea, Demick's book tells of six North Korean citizens living in the only country in the world not connected to the internet.
Its title comes from a song North Korean children are taught entitled We Have Nothing To Envy in the World.
"Nowhere will you find a better account of real life in North Korea," said Davis, who scrutinised the shortlist with Financial Times arts editor Jan Dalley and historian Stella Tillyard.
"I think we knew this book had something when we found ourselves reading it out loud to spouses and partners," he added.
The five runners-up - whittled down from an original longlist of 19 books - each receives £1,000.
Coverage of the ceremony features in Thursday's edition of The Culture Show, to be broadcast on BBC Two at 2320 BST.