The Arthurian legend gets a modern and more youthful spin in “The Kid Who Would Be King,” a surprisingly delightful film full of action, heart, a crazy-haired Patrick Stewart (as “old” Merlin) and a few genuinely good gags, and it really couldn’t have come at a better time.

It’s an Amblin-esque movie about fantasy, geek culture and outcasts that’s actually been made for modern kids — not nostalgic adults who crave both the cozy comfort of the things they grew up with, but, like, with way more violence, gore and nudity. “The Kid Who Would Be King” reclaims the fantasy genre for actual kids of today. And it’s not even set in the 1980s.

YOU CAN thank writer and director Joe Cornish for the restraint (although the score is pretty heavy on the synths). The film is his follow-up to “Attack the Block,” the cult sci-fi hit that helped put “Star Wars’” John Boyega on the map. Here he introduces audiences to some other young talents to watch, including Louis Ashbourne Serkis, Andy Serkis’ son, as the would-be-king, Alex.

Alex is a normal and slightly dorky lower-middle class British schoolkid, living with his mom (Denise Gough). He struggles with everyday stuff — waking up on time, completing his school assignments and protecting his buddy, Bedders (a truly wonderful Dean Chaumoo), from schoolyard bullies named Lance and Kaye, but he’s trying his best.

Then one night, running from Lance (Tom Taylor) and Kaye (Rihanna Dorris), Alex spots a sword in the middle of a construction site and removes it from the stone with ease. He and Bedders plug the inscription into Google translate and try to keep their imaginations in check when they realize that it might be real, but, both the audience and the boys will fail at this.

From here, the film just gets grander and weirder, with the introduction of Young Merlin (featuring a brilliant comedic performance from Angus Imrie), and the enemy, Morgana (Rebecca Ferguson). Morgana, we’re told, is Arthur’s power-crazy half-sister who has been waiting for centuries for the perfect moment to rise. Although Brexit isn’t explicitly mentioned, it is the not-so-­subtle context for all of this.

WHEN CREATURES start attacking at night, Bedders and Alex decide to enlist Lance and Kaye to help. They’re bullies, but they’re also the strongest, and Alex figures it’s worth the risk. And what follows is a big, classic quest as the four kids journey through the countryside and learn about sword fighting, the chivalric code, teamwork, trust, and the Lady of the Lake (who can be conjured in any body of water). Although basically unknowns, all the young actors have charm to spare and carry the film admirably.

“The Kid Who Would Be King” really is quite a sweet and well-told reimagining of this story that’s fit for the whole family. And it is refreshing that it’s not trying to be too dark or edgy, although it definitely overstays its welcome, clocking in at over two hours. But it’s a small price to pay for something so enjoyable on its own that might also just get some kids to start reading about Arthur and Lancelot as well.

“THE KID WHO WOULD BE KING”

***

(PG, 2:12)