If the idea of Sir Arthur Conan Doyle’s cerebral detective being converted into a modern action hero appeals to you, “Sherlock Holmes” will be your cup of tea—or rather your can of Red Bull. It’s precisely the sort of mindlessly revved-up, high-octane thing one expects from Guy Ritchie, and anyone who admires the Basil Rathbone-Jeremy Brett school of interpretation with find it a desecration rather than an updating. But even if you enjoy the over-the-top Ritchie approach, you may find that this movie has more in common with “The League of Extraordinary Gentlemen” than the better examples of it.

One of the film’s greatest strengths is certainly its look, which presents a meticulous portrait of gray, grimy nineteenth-century industrial London courtesy of production designer Sarah Greenwood, art directors Niall Moroney, James Foster, Nick Gottschalk and Matt Gray, set decorator Katie Spencer and costume designer Jenny Beavan. And it’s all lovingly photographed by cinematographer Philippe Rousselot.

But the narrative that’s played out against that backdrop, cobbled together by four writers, is a very silly business pitting the young Holmes (Robert Downey, Jr.) and Watson (Jude Law) against Lord Blackwood (Mark Strong), a nefarious nobleman who has apparently enlisted the powers of darkness to conquer not only the world but death itself. The convoluted business also involves a secret Mason-like society populated by political bigwigs like Sir Thomas Rotheram (James Fox) and Lord Coward (Hans Matheson), a royal minister, as well as Holmes’ professional and romantic nemesis Irene Adler (Rachel McAdams), who toys with the hero and turns out to be in cahoots with a figure even more sinister than Blackwood (cue a sequel). And all this is set against Watson’s upcoming nuptials with the lovely Mary Morstan (Kelly Reilly)—a circumstance that leaves Holmes at loose ends over the prospect of losing his long-time flat-mate and chronicler.

At the risk of being charged with heresy, it has to be said that some of Conan Doyle’s plots—particularly those touched with supposedly supernatural elements—weren’t all that great. (“The Hound of the Baskervilles” is a perfect example.) But he never structured them as a series of fight scenes periodically interrupted by goofy exposition and juvenile gags. This picture begins with a James Bond-like prologue in which Holmes disrupts a Blackwood subterranean ritual featuring human sacrifice (shades of 1985’s “Young Sherlock Holmes”), and then opts every fifteen minutes or so to interject an extravagant action sequence involving fisticuffs, martial-arts moves, clattering machinery and, most irritatingly, a heavily-muscled, unstoppable behemoth who resembles a nineteenth-century version of The Terminator. The big finale has Holmes, Blackwood and—for good measure—the dainty McAdams tussling on no less than the skeleton of an unfinished Tower Bridge. (It’s they, not it, that threaten to fall down. And before you write, yes, I know that Tower Bridge is not London Bridge.)

All the action is choreographed, shot and edited (by James Herbert) in Ritchie’s customarily hyperkinetic style that values the pow and the wham over anything else (though it must be admitted that Holmes’ application of his deductive abilities to a bare-knuckles match against a low-life bruiser is a nice touch). Otherwise, though, the cerebral side of the detective plays second fiddle to the physical, until at the close, like Hercule Poirot, he unravels it all for us, complete with flashbacks. Apart from that, it can be said with certainty that Doyle wouldn’t have resorted to bits that try to extract laughs from the feeble sight of a flatulent dog, or from the sight of his detective trussed up naked in bed after an evening romp with Adler (a pillow covering his private parts). Or that he would have tolerated Ritchie’s ludicrous bit of “style” in the form of a crow that reappears on cue as a symbol of Blackwood’s malice—or something. The bird shows up so frequently that you half-expect a reborn, white-faced Brandon Lee to accompany it. It becomes more intrusive than a flock of John Woo’s signature doves.

Still, “Sherlock Holmes” does afford some pleasure in the work of Downey and Law. The former may be more Downey (or Tony Stark) than Holmes, but it’s always fun to watch him do his verbal routines, though in truth he doesn’t seem entirely comfortable with some of the macho stuff. (Could the film’s reticence about Holmes’ drug use have something to do with the actor’s past indiscretions in that respect?) As Watson, Law proves a very proper British military man, as physically adept as Nigel Bruce was phlegmatic. Individually they’re enjoyable, and their interaction doubles the fun. It’s a pity they’re stuck in Ritchie’s misguided film. Nor do they get much support from the rest of the cast. McAdams is more irritating than engaging, Strong is boringly dour, and Reilly is nondescript. As for Fox, he’s coming to seem a waxworks figure, while Eddie Marsan makes a slapdash Lestrade. On the other hand, one wishes there were more of Geraldine James’s Mrs. Hudson.

To say that this is a “Sherlock Holmes” for today’s tastes is merely to admit how deplorable today’s tastes are. Happily, Rathbone and Brett are still available to provide the proper antidote.