As a devoted Benedict Cumberbatch groupie, it pains me to have to say that even the theatrical genius who dazzled us in Sherlock, and amazed us in Frankenstein cannot raise The Imitation Game—by Norwegian director Morten Tyldum—above the level of a made-for-TV Hallmark special.

Perhaps it was a hopeless task after all, attempting to express on-screen tension and drama about the creation of a code-busting device that anticipated today’s computers. Not exactly the visual equivalent of parting the Red Sea, is it? As mathematical innovator Alan Turing, Cumberbatch offers dazzling micro-gestures via twitching eyebrows, quivering lips, clenched (and unclenched) jaw, not to mention the required sort of physical awkwardness one expects of Cambridge geniuses. But these alone do not a film make. Even the surrounding cast of remarkably good-looking British actors (many recognizable from Downton Abbey) as Turing’s fellow code-breakers—plus the inappropriately glamorous Keira Knightley as the sole female cryptographer—do not convince us that any of the World War II cryptographic highjinks are film-worthy.

Turing was enlisted during the war by British MI6 to help break the German high command codes that delivered wartime instructions to the battlefield via an encryption device known as Enigma. He in turn, as we learn at length, set about building a programmable machine that would be able to break the German codes. As we know now, Turing and company succeeded in their top secret cerebral project, thereby shortening the war by two years and saving millions of lives.

Oh, and Turing was also gay at a time and place where this was illegal and punishable by imprisonment. Okay, so he’s a genius, a gay genius, and a law-breaking, repressed, gay genius. Turing’s untimely end (which I won’t reveal in case there is someone left in the free world who doesn’t know it) is the stuff of genuine drama.

Cumberbatch is arguably among the finest three actors working today. But the Nordic director just couldn’t connect those dramatic dots.  Instead he shows us Turing twitching. Turing pissing off his fellow cryptographers because he’s just that odd a sociopath. Turing finally getting close to the “solution.” Turing having an “aha!” moment. Turing rushing around twisting knobs and dials. Turing and company cheering and hugging when it all works out. All that was missing was voice over narration by David Attenborough.

Seriously. Even Cumby couldn’t rise above this dumb and pedestrian material. There’s no gay subtext tension, save through the flashbacks to Turing’s youth at boarding school and his pivotal (dare I say “seminal?) friendship with a fellow savant. As the young Turing, Alex Lawther is spectacular. A much better film would have been a documentary about Alan Turing and his top-secret computing project, with narration by Cumberbatch himself. His voice alone could part the Red Sea even better than Welshman Christian Bale.

The multi-valent, theatrically dazzling Cumberbatch deserves better material. Much better material. Perhaps he is spreading himself too thin. Or is in need of a new agent, one with standards high enough to match Cumberbatch’s stupendous abilities.

Code-breaking, World War II, Cumberbatch as painfully gay mathematical marvel Alan Turing. . . there’s a lot of great material here. But none of it is in The Imitation Game.