It’s hard not to attribute the existence of this new Arthurian tale in part to the global success of “Game of Thrones,” which has hooked legions on its epic soap opera, clashing swords, spurting blood and unending intrigue. (That show’s Aidan Gillen pops up here too.) The Arthur story has played out differently across the centuries, from the Middle Ages to T. H. White’s novel “The Sword in the Stone” to Disney’s 20th-century cartoon take, and each moment in time shapes the way it’s told. In this case, that means something old, something blockbustery and that Guy Ritchie je ne sais quoi.
Put differently, this variation on the Arthurian legend fleetingly brings to mind “Game of Thrones” but mostly plays out according to the Ritchie template: a self-amused, endlessly resourceful laddish hero gets in and out of trouble with winks, smarts and brute force, sometimes in the company of Jude Law. This time the resident rogue is Arthur, played with easy, low-wattage charisma by Charlie Hunnam, who has a gift for delivering nonsense without seeming embarrassed. Mr. Law, who played Watson in Mr. Ritchie’s “Sherlock” flicks, takes on mustache-twirling duties as Vortigern, a louche pouter who skulks around in black, doubtless dreaming of Richard II.
Arthur and Vortigern mix it up amid a lot of shenanigans, detours and filler, some bad, some good and all of it disposable. Written by Mr. Ritchie, Joby Harold and Lionel Wigram, the movie is mostly about establishing Arthur’s origin story, which turns on the usual reluctant hero coming to terms with his destiny, meaning Dad (Eric Bana) and Dad’s mighty sword. This lineage and its burdens take a while to work through, primarily because this movie plays like the first installment in a hoped-for series. Merlin scarcely makes the scene, and Guinevere and Lancelot have yet to arrive to stir up trouble.
The opener is a clotted visual mess, which isn’t surprising. But it is disappointing just because the whole thing — the landscape, castle and so forth — is so drearily fake and ugly, even if the elephants are kind of amusing and it’s always nice to see Mr. Bana. The movie improves once Mr. Ritchie moves closer to his actors, a pleasantly diverting crew that includes Djimon Hounsou as a fixer extraordinaire and Astrid Bergès-Frisbey as a witchy woman of some type. They help sell the generic goods — basically, a band of merry, dirty dozen (or so) smarty-pants renegades giving it to the Man — and the results are easy enough to watch, especially if, like Mr. Hunnam, you don’t embarrass easily.