The fairy tale known as “Jack and the Beanstalk” centers on a hapless kid who stupidly accepts “magic beans” for his widowed mother’s most valuable asset, a cow, and then, when those beans lead him to a foreign land, becomes a man by stealing from and killing a murderous giant. Director Bryan Singer’s Jack the Giant Slayer alters the thrust, but with a knowing sense of humor: The movie opens and closes with the suggestion that tales change in the telling, often depending on their era. And so, in ours, we get megabudget revisionist fairy tales in which familiar characters (Snow White, Hansel and Gretel, Alice of Wonderland) lock and load and then lead armies against the forces of darkness. Jack the Giant Slayer is easily the most amiable picture to come out of this new fairy-tale-action genre, hitting its studio-prescribed marks without making you feel as if you’re being marketed to (even if you are). And it’s fast, rousing, and blessedly brief — under two hours instead of, say, nine in three bladder-straining installments.

It’s almost Jack and Jill the Giant Slayers, since there’s now a love interest, Princess Isabelle (Eleanor Tomlinson), and she’s just as eager as young Jack (Nicholas Hoult) for adventure. In case you miss the soul-mate aspect, Singer cuts back and forth between two identical conversations — commoner Jack with his mingy-minded uncle, regal Isabelle with the king (Ian McShane), who insists she marry an older man named Roderick (Stanley Tucci). Think Moonrise Kingdom with cannibals. When the beanstalk carries Isabelle into the clouds, heights-hating Jack hauls himself after in pursuit — along with a company of soldiers led by Ewan ­McGregor (who does a very likable pip-pip, tallyho turn in what is, narratively speaking, not much of a role). There’s a touch of camp in the manly camaraderie but a lot of serious killing — some men fall miles to Earth, ­others get their heads bitten off — to balance it out. That’s what Singer does well: balance what he must do (as a studio hack) with what he wants to do (as an artist who wants to be able to look at himself in his own mirror, mirror).

Singer’s most obvious affinity is for the giants. They’re mean, slobby, man-eating CGI brutes, led by a two-headed general called Fallon (voiced by Bill Nighy). But they’re also rather poignant, lonely in the way of Sendak’s Wild Things, having been exiled to this stratospheric wilderness by Erik the Red, whom they call “Erik the Terrible.” Apart from a giant chef who rolls humans in pastry blankets (alongside actual pigs), the most hateful characters are human: Tucci’s Roderick, showing a Terry-Thomas gap in his teeth as he smiles at his own dastardliness, and Ewen Bremner as his giggly henchman. You come away thinking that the world is more complicated than humans versus giants — that the answer isn’t killing the brutes but exploring in, say, a good liberal editorial “Our Giant Problem.”

Movie Review: Jack the Giant Slayer