Transcript for Oscar Contender: Benedict Cumberbatch Opens Up

His name may be a mouthful. But it's almost a household one this awards season. Benedict Cumberbatch now enjoying his first Oscar nomination and newfound status as Hollywood sex symbol. It's a lot to take in for someone so private. He doesn't even have a Facebook account. Tonight Rachel smith draws him out for our series "Oscar confidential." Reporter: You could call him an overnight sensation. Or one of Hollywood's unlikeliest sex symbols. This is Benedict Cumberbatch. And these are the fans who lovingly call themselves cumb cumberbitches. That word, crumb cumberbitches. Most of them are sane, lighthearted people. Reporter: Now celebrating his first-ever Oscar nomination. For computer genius Alan turing and "The imitation game." How do you feel about the words Oscar buzz? In truth it means more people will be interested in seeing the film, more people will get to hear Alan turing's story, and that makes me very happy. My machine will work. Reporter: Based on a true story, Cumberbatch's character builds a machine that deciphers the nazi secret code during world war ii. He spearheaded this intelligence effort that Winston Churchill was wise enough to recognize as being the most important asset to winning the war at that stage. Greatest encryption device in history and the Germans use it for all major communications. Reporter: Winning the war didn't prevent turing from a devastating fate. After british authorities discovered he was gay he was charged with acts of indecency and sentenced to chemical castration. The court case was very public, he was shamed, he was in the papers. He took his own life at the age of 41. 5 minutes 34 seconds. You said to do it under 6. Reporter: Cumberbatch's career and popularity took off with his role in "Sherlock." The name Sherlock Holms and the address is 221 B baker street. Reporter: Despite his internet popularity Cumberbatch isn't on social media. I Benedict Cumberbatch am not on Twitter, instagram or Facebook. There are many people on instagram calling themselves me, it ain't me. Reporter: He managed to nearly break the internet when word spread of his impending cumber-baby due this year. How is Sophie taking all this? Great, she's very cool. Even about the cumber following? She's fine. True fans know intruding on something very dear and private for me -- Seriously private. It should be. There's somebody who's going to come into the world as our child. I ask people to respect that fact. Reporter: If there's one thing that's certain, 2015 promises to be a big year for Cumberbatch. When you take a step back and you reflect, what do you see? Looking back isn't something I want to do at the age of 30. I'm looking forward if anything. Very happy with who I am. Reporter: For "Nightline" I'm Rachel smith in Los Angeles.

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