“Sometimes it is the people who no one imagines anything of who do the things that no one can imagine.” What’s that you say, The Imitation Game? “Sometimes it is the people who no one imagines anything of who do the things that no one can imagine.” Maybe a third time for good measure. “Sometimes…” Okay, that’s enough. Repeated three times during the course of this handsomely mounted and mostly compelling biopic, that line is part of a hard sell on the offbeat genius of Alan Turing, the British mathematician credited with breaking Enigma, the seemingly unbreakable Nazi cipher machine. According to the closing credits, Turing’s brilliance helped end a war that could have cost 10 million more lives, and he laid the foundation for the early computer, as well as the notion of machines assuming an artificial intelligence. In other words, this is a very important film about a very important man, and the gravity the film assigns itself is easily the worst thing about it. It’s much better as a superficial war adventure about counterattacking math wonks. 

The constant in The Imitation Game is Benedict Cumberbatch’s terrific performance as Turing, which has much in common with his delightfully mercurial Sherlock Holmes, but with an underpinning of repressed emotion and quiet despair. Without identifying his place on the spectrum, the film posits Turing as an Aspergers type whose savant genius came easier to him than the social niceties necessary for him to function under military protocol, or as part of a larger team. His disrespect for authority puts him at odds with his boss (a deliciously haughty Charles Dance) at Bletchley Park, the hosting site for government codebreakers, and it immediately turns off his teammates, led by Hugh Alexander (Matthew Goode), a chess champion who isn’t used to having his intelligence questioned. Going straight to Winston Churchill himself, Turing succeeds in requesting a huge investment in a machine that could break the Enigma code, but that greatly increases the pressure for his fractured unit to deliver. Turing also makes waves by bringing on Joan Clarke (Keira Knightley), a fellow cryptology wizard who enters this exclusively male field. 

The Imitation Game flashes back to Turing as a grade-school boy (played by Alex Lawther), furtively pursuing his same-sex attraction. It was a crime then and a crime after the war, when he was charged with “gross indecency” in 1952 and committed suicide two years later. Young Turing is shown passing notes to the object of his affection, but in a private, coded language only they can access. The connection between Turing’s sexuality and his yen for cryptography isn’t particularly subtle, but it’s nonetheless an affecting metaphor for a life devoted to secrecy—the secrecy of his desire, the secrecy of Nazi messages, and the tacit codes of social conduct that Turing found so daunting. Cumberbatch at times suggests a man who identifies more with machines’ cold rationality than mankind’s petty motives, but Turing’s sensitivities poke through the performance, too, belying the notion that he’s unaffected by those around him. He’s just a turtle with an exceptionally hard shell.

Director Morten Tyldum (Headhunters) gives the film an old-fashioned prestige sheen that’s as unadventurous as its subject is idiosyncratic, but there’s a race-against-the-clock kick to Turing’s mission to crack the Nazi code and turn the war in the Allies’ favor. Cumberbatch has the ability to spin Turing’s absence of tact into comedy and pathos, depending on the situation, and even at Turing’s most callous and wounding, Cumberbatch has a way of making his incomprehension touching, like that of a baffled child. The Imitation Game pumps up Turing’s importance as a way of asserting its own, but it’s ultimately a case of a serviceable entertainment that can’t find a form worthy of its subject’s achievements or its lead actor’s performance. Both deserve a little better.