World War II, for those a little rusty on their history, wasn’t won by Brad Pitt or General Patton or Captain America. It was won by a bunch of nerds led by a socially inept, puzzle-obsessed mathematical genius who also happened to be homosexual at a time when homosexuality was illegal in Great Britain.

Their work, breaking enemy codes, was “Ultra” secret, the ultimate secret of the war. Ironically, it was entrusted to a man who was already quite accomplished at keeping secrets in his personal life.

“The Imitation Game” is an entertaining, sometimes riveting and yet quite conventional film biography of Alan Turing, the glum but gay Brit who invented the first electronic computer and thus created the modern world.

Graham Moore’s screenplay, based on an Andrew Hodges book, frames Turing’s story within a police case. A Manchester detective (Rory Kinnear) investigates a 1951 break-in at Professor Turing’s home, and is so put off by his aloof insults that he digs into who Turing really is and what his war record was. Detective Nock can interrogate the Great Man all he wants, but he must “Pay attention. I will not pause, I will not repeat myself.”

Norwegian director Morten Tyldum’s film flashes back to Turing’s comically brusque first meeting with his would-be Royal Navy boss (Charles Dance, biting), his incompetence at mixing with his code-cracking teammates and the stroke of genius that had him go directly to Churchill, through the MI-6 intelligence chief (Mark Strong, wonderfully inscrutable) to take over the team.

Turing’s brainstorm — only a machine can defeat another machine, the German Enigma encoder. He will build an electronic device that can sift through the coded Morse Code letters of German transmissions fast enough to save convoys, head off attacks and foil the fascists, who were winning the war pretty much right up to that moment.

There were threats from the Admiralty, security breaches involving leaks to the Soviets and personality clashes along the way.

“Damn you and your useless machine!” shouts fellow code-breaker Hugh Alexander (Matthew Goode, effortlessly suave and caddish), not knowing a cliche when he bellows one.

Turing is forever insulting his peers and failing to apologize with more than “That’s actually not entirely a terrible idea.”

He uses crossword puzzle tests to recruit help, among them, a woman (Keira Knightley) whom he cannot even invite into the office with the other men. Turing and Joan Clarke had to meet after hours and ponder the problems of Enigma — a secret within a secret within a secret.

And we travel back to Turing’s boarding school days, his first hint of love, which is meant to further reveal his character. The boy playing young Alan, Alex Lawther, is even more convincing as a guarded, eyes-averting genius with a “dirty” secret than Cumberbatch, who is at his best here.

Tyldum’s film recreates the consequences of the war in quick, digitally-augmented scenes of convoys sinking, bombs falling and battles raging. Moore’s script ably ramps up the pressure on the team. It does a poor job of showing the tragedy of Turing’s hidden life but a better job at making a bigger case — unconventional people make unconventional thinkers.

When you’re tackling “the most difficult problem in the world,” you need all the unconventional people you can find.

MPAA Rating: PG-13 for some sexual references, mature thematic material and historical smoking

Cast: Benedict Cumberbatch, Keira Knightley, Matthew Goode, Charles Dance, Mark Strong

Credits: Directed by Morten Tyldum, screenplay by Graham Moore, written by . A release.

Running time: 1:54