It's said that one man shortened World War 2 by at least eighteen months, saving thousands, perhaps millions of lives in the process. He did it with sharp pencils, a sharper brain and effectively invented the computer along the way.

Alan Turing's ground-breaking technologies broke the 'unbreakable' Enigma code on which the Nazi's depended for sending encrypted communications around the world. With that knowledge in their pocket, the Allies slowly gained ground on their enemy, forcing Germany into a showdown that would end the war. All of which makes for a fascinating account.

Yet Morten Tyldum's The Imitation Game is not really that story. There's barely a gun to be seen on the government compound where Turing and his mathematicians worked day and night to solve the riddle. This is much more intimate, revealing how the arrogant Turing was unable to form profitable relationships, how he cracked the code and eventually came out to his fiancée. It's much less about a world war than the battle with his own, internal struggles. And it's no less fascinating.

At its heart is a career defining performance from the always excellent Benedict Cumberpatch (The Fifth Estate) who reveals all of Turning's conflictions with little more than a twitch or a longing stare. It's what he doesn't do, or doesn't say, that makes his character all the more mesmerising and his performance all the more riveting. Not that he's a one man machine. Matthew Goode (Stoker) as the personable brain Turing's team rallies behind, or Keira Knightly (Anna Karenina) as the woman in his life give Cumberpatch plenty to work against. Mark Strong (Zero Dark Thirty) and Charles Dance (Game Of Thrones) shore up the rear guard.

Turing's story has been told in Michael Apted's problematic Enigma. The difference here is Tyldum's winning decision to make his film part procedural, for despite Turing's significant achievements, the man has a secret which no one can afford to have in the early paranoia of a war turning from hot to cold. Once the police force turns on him – is he a double agent? – The Imitation Game gains a powerful level of emotional intensity as they lay waste to one of the best minds. Factor in a richly layered narrative supported by elegant, classical production and you've got one of the best films of the year. Not bad, considering it's only the first of January.

// COLIN FRASER

Previewed at Events Cinema, Bondi Junction, Sydney on 4 December 2014