THIS fantasy/actioner, which doesn’t open in the US until next week, has crept up on Australia with little if any warning.

After a stylishly-animated introduction summarising the Arthurian legend, writer/director Joe Cornish’s second feature segues to a London suburb and a house in Malory Street (readers of the principal account of the legend will from one quick glimpse note one of the film’s several references to that literary source).

After breakfast, Alex (Louis Ashbourne Serkis) goes off to Dungate school, where he comes to the aid of Bedders (Dean Chaumoo) when older kids Kaye (Rhianna Dorris) and Lance (Tom Taylor) pick on him.

We’ve now met all but one of the film’s principal juvenile characters. Their names have Round Table links. The fifth is a young magician who introduces himself as Merkin (this brief reference to pubic wigs is as far as the film goes in that direction) then admits that he is actually Merlin, that he commands great magic and when he needs to travel he transmutes into an owl (traditionally the symbol of wisdom).

But before this, on a building site Alex has found and withdrawn the sword Excalibur from where Arthur left it before dying. In the underworld, King Arthur’s sister Morgana, claiming to be Arthur’s heir, bound to a cave wall by an entanglement of tree roots, is not pleased. It’s a while in film time before she turns up again in her dragon guise at the head of a horde of mounted riders wielding flaming swords to try to claim what she considers to be her rightful inheritance. It’ll be up to Dungate’s pupils to defend the world against them.

As the story develops, we see that it’s more than merely a fantasy adventure. It’s a message movie for our time. And young folk are getting the message. After the session when I saw it, an adolescent accompanied by his younger sisters gave it a grinning thumbs up. A mother with three school-age daughters told me that they would be discussing it at the dinner table. On a heatwave day it delivered a refreshing, sobering and very entertaining reminder that today’s adults and their predecessors have bequeathed to tomorrow’s adults a global mess for them to tidy up.

That and some truly delightful and clever special effects are why “The Kid who would be King” gets those four stars.

At Capital 6 and Limelight