I watched the new Harry Potter movie yesterday, and thought it was pretty good. I’m not sure it was good enough to justify its 78 score on Metacritic, but it’s competently executed, and the film-makers have largely succeeded in their efforts to create a darker Harry Potter that corresponds with the increasing maturity of the books. Thankfully, we’ve come a long way from the days when the extraordinarily banal Chris Columbus was in charge of the franchise.

Still, there’s something missing from this movie. Most of the criticism of The Half-Blood Prince has focussed on the preponderance of teen romance, which is juxtaposed somewhat awkwardly with the good vs. evil A-plot. Personally, I didn’t mind this much. However, I did think the A-plot was underdeveloped. In JK Rowling’s version of the story, Harry Potter and the Half-Blood Prince was a thinly-disguised analogue of the War on Terror. The book never lets the reader forget that, even though events at Hogwarts are proceeding more-or-less normally, in the wider world there is a war of national survival taking place – and moreover, it is a war that the Ministry of Magic is losing badly, even though the hawkish neocons under Rufus Scrimgeour have temporarily wrested control away from both Cornelius Fudge’s pacifists and the outright pro-Voldemort fellow travellers like Dolores Umbridge. (It is the latter group, of course, that eventually ends up in control of the Ministry.)

By de-emphasising the politics, the film makes the war itself seem distant and unimportant. When acts of terrorism do occur, they seem absurdly disconnected from any form of strategic logic. In the opening scene, Voldemort’s Death Eaters destroy the Millennium Bridge, for reasons that are frankly unfathomable. Then Voldemort sends his strongest lieutenant, Bellatrix Lestrange, to… well, burn down the house of Arthur Weasley, a mid-level bureaucrat who works in an unimportant government department. It’s hard to detect any kind of calculated genius behind Voldemort’s attacks, and this is partially why the sense of dread and helplessness that pervades the book is largely absent from the movie.

Speaking of Bellatrix Lestrange, I have one final complaint. Why is it that Helena Bonham Carter was (mis)cast in this role? Hollywood operates on autopilot a lot of the time, and this seems to have been one of those occasions. Film studio executives view Bonham Carter as a freaky goth chick who has been in lots of Tim Burton movies, so why not cast her as evil witch? Makes perfect sense, right? Except that Bonham Carter comes across more like a crazy bag lady – a variation on her character in Fight Club – than the powerful and dangerous villainess in the books. The casting director ought to have exercised a little more imagination in this case.