Sherlock, Series 2, BBC One

My, but it’s been a bumper few months for the Baker Street Boy. There’s been Anthony Horowitz’s superior new Holmes novel, The House of Silk, Guy Ritchie’s second instalment of his steampunk take on Sherlock as karate-kicking action hero, and now the return of the BBC’s stylish reboot of Holmes as a new millennium net 'tec. And what a lot of fun it was.

The first of three new 90-minute films began where the last series left off, reviewing the stand-off between Holmes ( Benedict Cumberbatch) and Watson (Martin Freeman) and the psychopathic “consulting criminal” Jim Moriarty (Andrew Scott, whose resemblance to Dec from Ant & Dec only slightly dulled his see-sawing menace).

It proved to be the last we saw of Holmes’s arch-rival until very near the end of this episode, though he cast a long shadow. Entitled A Scandal in Belgravia, the plot stuck surprisely close to the broad outline of A Scandal in Bohemia, one of Conan Doyle’s raciest tales. The Bohemian Grand Duke of Cassel-Felstein in the original story had become a (female) member of the British royal family, snapped in a series of compromising positions with Irene Adler (Lara Pulver, pictured left), recast as a high-end dominatrix who, in Mycroft’s peerless phrase, provided “recreational scolding” to the rich and powerful. Considerably cooler and smarter than Holmes's estimation of the average female of the species, Adler had made the royals aware of the existence of the slap-happy snaps and Holmes was duly employed to get them back. And so the game was afoot. A game of equals. Almost.

The plot – taking the original spirit of the Holmes stories and going hell-for-leather – was confused, convoluted nonsense, like one of those head-spinning Ted Rogers riddles that would eventually lead to Dusty Bin. It encompassed the mysterious murder (by boomerang, it transpired) of a man in a remote hillside, several set-tos with US spooks, a faked death, bluffs and double-bluffs, after all of which it became clear that the spanking of the royal rear (which put quite another spin on the phrase blue blood) was a red herring, diverting attention from a more sinister terrorist plot to blow up a jumbo jet. While whipping some high-ranking civil servant into a frenzy Adler had captured on her camera phone vital information pertaining to the plot, and, using her womanly wiles, later snared Holmes into deciphering the clue. She then fed the info straight to Moriarty, who informed the terrorist cells – and well, yes, it all eventually got more than a little silly.

But 'twas ever thus with Holmes. Sherlock was overlong and eventually ran out of puff, but it was successful utimately not because of the tale itself but for the stylish and entertaining manner in which it was told. Cumberbatch (pictured below right) is a joy, bringing a marvellously jaded wit to Holmes, while Freeman quietly excels as his deadpan cohort. Together they enjoy a terrific rapport, capturing the odd bond shared by the pair. They were well served in A Scandal in Belgravia by Steven Moffat’s whip-smart script, which gave them both killer lines while also dishing up winking in-jokes (a deerstalker and a blog post called "The Speckled Blond" among them), and which was altogether fast, funny, clever and literate. Paul McGuigan’s direction, meanwhile, was endlessly inventive, doing its utmost to keep pace with the squealing handbrake turns of Holmes’s mind.

There was sport to be had with the royal connections. Holmes pitched up in Buck House having been dragged from his manky flat (when Una Stubbs’s Mrs Hudson opened the fridge she picked up something in a plastic bag and yelped, “Oh dear, thumbs!”) wearing only a bed sheet. “We are in Buckingham Palace, the very heart of the British nation,” growled brother Mycroft, played with a lovely upper-crust ennui by the show’s executive producer Mark Gatiss, “Sherlock Holmes, put your trousers on.” Cue much schoolyard giggling from Holmes and Watson.

Cumberbatch and Pulver, meanwhile, had a whale of a time making brainy the new sexy (although both were more than adept in the "making sexy the new sexy" department, too). The episode could have been subtitled The Sexing of Sherlock. Adler was, famously, the closest Holmes ever came to being bested by a woman; indeed, he ever after referred to her as “the woman”.

You could see why. She made a memorable entrance wearing nothing but a predatory smirk, and for a while it looked as though Holmes, snared in an erotically charged game of cat-and-mouse, had for once had his interest engaged somewhere due south of his brain. But not so fast. This, it transpired, was the kind of man who takes a woman’s pulse when she’s propositioning him in order to dust for any traces of that most deadly emotion, sentiment.

For in the end the winner in this grand game of wits was determined not by the criminal ending up in the arms of Inspector Lestrade, but rather with the reveal that one of the pair had been playing for genuine emotional stakes. Not only her quickening heartbeat but also the crucial codeword protecting the secrets in her camera phone revealed Adler's passion for the detective. Thus, she lost. Holmes too, however, displayed signs of a hot heart beating hard somewhere beyond the freeze-chilled brain. And that tell-tale code? It read: I AM SHERLOCKED. You could kind of see where she was, um, coming from.

• Sherlock: The Six Thatchers reviewed on theartsdesk