HOW skilled a secret keeper is Benedict Cumberbatch if he readily confesses the easiest method for extracting secrets from him?
Asked somewhat frivolously for information about one of the many coming projects he cannot talk about, Mr. Cumberbatch, the 35-year-old British actor, offered an equally facetious response.
“You could stick a knife in my thigh, and I wouldn’t tell you,” he said a few weeks ago, relaxing on the deck of the Venice, Calif., home where he was staying. But he added: “Pull the hair on my head the wrong way, and I would be on my knees begging for mercy. I have very sensitive follicles.”
Deeper still within his head were numerous vital details that Mr. Cumberbatch’s work required him to keep locked away. There was not much he could say about his dual roles as a necromancer and a talking dragon in Peter Jackson’s film adaptation of “The Hobbit,” and even less about the part he was shooting in J. J. Abrams’s sequel to “Star Trek.” (“I’ve got to be a complete and utter tease,” he said, more gleeful than apologetic.)
What Mr. Cumberbatch can confirm is that these high-profile opportunities were made possible by the success of “Sherlock,” the television series that casts him as a cool and contemporary — if brutally rational — upgrade of Sherlock Holmes. It returns on May 6 for a second season on PBS’s “Masterpiece Mystery!”
In Britain, where “Sherlock” is shown on BBC One, the series has left millions of fans frantic to know the resolution of a season-ending cliffhanger, which American viewers have not yet seen, and transformed Mr. Cumberbatch (who already knows the outcome) from a well-regarded journeyman actor into a superstar.
And he makes no secret of his desire to see “Sherlock” enjoy similar acclaim in the land of “Mad Men” and “Modern Family.”
“I’m desperate for America to really take to this,” he said. “It has taken it into its heart as a cult thing, but I’d love it to hit the mainstream this time. Because I just think it’s of that quality, and it belongs there.”
In person the thin and muscular Mr. Cumberbatch shares the piercing gaze and sonorous, sinister voice of his Holmes but is warmer and more irreverent. He is a self-confessed motormouth and a relentless mimic who, over the course of an hour, adopted the shrieking voice of an admiring Valley girl; the Scottish burr of his friend and colleague James McAvoy; the synthesized speech of Stephen Hawking, whom he portrayed in a British TV movie; and the rapid, adenoidal clip of both Mr. Abrams and Steven Spielberg, who directed him in “War Horse.”
In similarly haphazard fashion Mr. Cumberbatch has spent the past 18 months ricocheting from role to role, in British stage productions like “After the Dance” and “Frankenstein” (for which he shared the Olivier Award this month with his co-star Jonny Lee Miller); a coming television version of “Parade’s End,” adapted by Tom Stoppard from the Ford Madox Ford novels; and films like “The Hobbit,” “War Horse” and “Tinker Tailor Soldier Spy.”
Last December, on vacation in Gloucestershire, England, he got the call that Mr. Abrams wanted him to submit a videotaped audition for “the not-so-good guy” (in Mr. Cumberbatch’s words) in the “Star Trek” sequel — and could not find anyone to film it for him.
“We observe this little Judeo-Christian cult holiday called Christmas,” Mr. Cumberbatch said sarcastically. “Whereas, you know, some kids in this part of town” — he circled his hands in the Los Angeles air — “with their Crackberrys, don’t.”
In a friend’s kitchen late at night, an agitated and weary Mr. Cumberbatch recorded his audition on an iPhone — “I was pretty strung out,” he said, “so that went into the performance” — and sent it to Mr. Abrams, only to be told the director was also on vacation.
Mr. Abrams, who saw the recording a few days later and hired Mr. Cumberbatch, wrote in an e-mail that it was “one of the most compelling audition readings I’d ever seen.”
But Mr. Abrams already knew this from Mr. Cumberbatch’s work on “Sherlock,” whose second season drew around 10 million viewers in Britain for each of three 90-minute episodes shown in January, according to the Broadcasters’ Audience Research Board. (By contrast, in the United States, the first season averaged 4.6 million viewers per episode, PBS said.) On Tuesday, Mr. Cumberbatch’s work on the show earned him a Bafta award nomination for best actor.