In the second-season finale of the BBC's Sherlock, the detective hero (played by Benedict Cumberbatch) leapt off a roof. Sherlock Holmes was pronounced dead on the bloody sidewalk. Then, in the final shot, as Martin Freeman's devoted Dr. Watson grieved by his grave, Holmes appeared in the distance – very much alive.
The episode set off a roaring debate among fans leading up to the show's third-season premiere (airing stateside January 19th on PBS). "Everybody had their own theory," says the show's co-creator, Steven Moffat, who also runs the rebooted Doctor Who. "Every newspaper in England had a theory!"
The cinematic 90-minute premiere kicks off a season that plays like an orgy of wish fulfillment for fans. The cases are as wild as ever, but the relationship between Holmes and Watson deepens. In the second episode, the hyperlogical Holmes has to deliver a best-man speech at Watson's wedding; riotous flashbacks reveal the pair's earlier soused adventures. "Holmes is a known substance abuser – he injects cocaine in the original books," says Moffat. "We thought: What about Sherlock drunk? Getting absolutely pissed? I'd like to see that."
The show's global success – it's a smash in the U.K. and a rapidly growing cult hit here, and 3 million fans watched the premiere online in China – owes much to the chemistry between Cumberbatch and Freeman. Fans have taken to writing homoerotic slash fiction about a Watson-Holmes romance. "Sherlock Holmes has always been a sex symbol," says Moffat. "The most attractive person in the room is not always the best-looking; it's the most interesting."
Holmes, as played by Cumberbatch, isn't always likable. "He likes to think of himself as a highly functioning sociopath," says Moffat. "More accurately, he's someone who wants the excuse of being a sociopath so that he doesn't have to do the things that bore him."
The showrunner emphasizes that his Holmes isn't a Vulcan with no emotions – he's simply decided that things like sex and jokes would interfere with his deduction. "It's the decision of a monk, not an affliction," Moffat says. "It's an achievable superpower."
The imminent danger of Season Three is that Holmes' icy facade might finally crack. "He is not wrong to be distrustful of his emotions," says Moffat. "And he will learn this ruefully in the final episode."
This story is from the January 30th, 2014 issue of Rolling Stone.