This time around, Watson's sustained his injury in Afghanistan again, but as part of British forces supporting the post-9/11 American invasion. Perhaps fittingly, given that depressing repetition of history, Martin Freeman's Watson is a wiser and sadder than his literary predecessor. Rather than a lingering fever, he has an unhelpful therapist who encourages him to blog. But he still has a handy service weapon and a wholly inadequate military pension. He's isolated by his service rather than ennobled by it: there are no other veterans in his life, and his therapist misdiagnoses him and doesn't help him get out into the world. "You're a war hero who can't find a place to live," Holmes says in one of their early conversations, underscoring Watson's alienation from his remaining relative, his alcoholic lesbian sister.

Freeman's turned-down mouth and turned-up nose have often served to cast him as a sweetie, as he was in the original version of The Office, or a naif, as he was as Arthur Dent in Hitchhiker's Guide to the Galaxy. But in Sherlock, Freeman imbues those features with a real grimness. He lacks some of the original Watson's capacity for amusement, but he isn't a post-traumatic wreck. He's got a yen for action that paces Holmes' own. In his flatmate, he finds not simply an entertaining curiosity but a revivifying partner.

Watson's Afghan service isn't the new miniseries' only deftly tweaked update to Conan Doyle's creation. Sherlock's brother Mycroft Holmes, a lazy genius employed by the government and described in the stories as "the most indispensable man in the country," is now a figure of considerable importance in the British surveillance system. Instead of the urchins who filled the ranks of the Baker Street Irregulars, a Banksy-like graffiti artist shows up to offer advice and pass the blame for his latest piece to Watson in the second episode, and an enterprising homeless woman appears in the third. And the long-suffering Mrs. Hudson now has enough black humor to cluck at the man keeping a skull in her apartment, "I'm your landlady, not your housekeeper," and to cut him a break on the rent because he helped speed the execution of her late husband.

But these references to contemporary events are only part of why the decision to move Holmes to contemporary London makes so much sense.

At the heart of Holmes' deductive brilliance are two somewhat divergent tendencies: a devotion to the expanding scientific knowledge and mastery of the trivial. When we first meet Holmes in both Conan Doyle's stories and this adaptation, he's beating corpses in a mortuary to see how long after death they continue to bruise. All of today's fictional portrayals of modern, scientific, and psychological detection owe a debt to Sherlock Holmes. It's only fair he should get a shot at taking advantage of scientific progress in solving a new set of crimes—or paternity cases on talk shows. "Of course he's not the boy's father!" Holmes splutters, watching television. "Look at the turnups on his jeans!"