Giving a spellbinding performance, Benedict Cumberbatch unlocks the secrets of mathematician and cryptographer Alan Turing.

A prickly, arrogant and anguished genius, he cracked the Nazis’ Enigma code during World War Two and paved the way for modern computing.

Passing back and forth between Turing’s schooldays in the 1920s, his wartime codebreaking at Bletchley Park and the aftermath of his arrest for homosexuality in the 1950s, this film is at its most compelling during the war years.

Charles Dance’s bristling naval commander and Keira Knightley’s brainbox provide excellent support, but it’s Cumberbatch’s performance that keeps us rapt.