The story of how Alan Turing and the Bletchley boffins defeated the Enigma machine is one of the most stirring of the Second World War; the British David conquering the Nazi Goliath by virtue of superior mathematics and intellectual daring.

The Imitation Game is a polished, well-paced account of these code-breakers that broadens the scope to encompass an exploration of Turing's outcast status in a society wary of his genius and unprepared to accept his homosexuality. It may have an old-fashioned sweep and a cautious approach to some of the darker elements of Turing's life, but the sheer emotional force of the piece and the virtuosity of Benedict Cumberbatch's central performance make it hard to resist.

Based on Andrew Hodges' biography Alan Turing: The Enigma and marking the English-language debut of Norwegian director Morten Tyldum (Headhunters), The Imitation Game begins with Turing's arrest in 1951 on charges of 'gross indecency'. Flashbacks to his schooldays and his years at Bletchley Park paint a touching account of a man with few intellectual equals and even fewer social graces.

Turing alienates his colleagues, exasperates his military masters (embodied by a splendidly starchy Charles Dance) and seems blithely unaware of the impact his blunt candour has on those around him. His rational mind also makes him blind to the sexism of his era as he becomes a fond champion of Joan Clarke (Keira Knightley in Celia Johnson mode), an equally formidable intellect with the disadvantage of being a mere gel.

The Imitation Game is a triumphant slice of British heritage drama boasting thoroughly engrossing cloak-and-dagger intrigue, as brilliant brains battle impossible odds to save millions of lives. And Cumberbatch's flawless, touching portrayal of a beautiful mind and a tortured man pushes it into the arena of 2014 Oscar contenders.

Screening as part of TIFF 2014. General release from Fri 14 Nov.

The Imitation Game - Official Trailer - The Weinstein Company