Two years after J.K Rowling took George Lucas’s hand and jumped through the prequel portal, to the hidden city of Diminishing Returns, we have this second Fantastic Beasts movie; an attempt to convince us that a series based on a thin charity volume was the springboard for an exciting and necessary expansion of the Harry Potter universe. Sadly, once you start thinking about the Star Wars prequels, it’s very hard to shake the idea that The Crimes of Grindelwald represents a similar folly, and I don’t mean the casting of alleged spouse abuser, Johnny Depp. It’s a story that makes the parent world smaller by following a similar trajectory to the original stories but with markedly duller characters. Not only that, Rowling shows a similar cavalier approach to her, I suppose we have to say, classic creations, risking the ire of a rabid fanbase who would prefer to imagine the backstory for themselves. Just Dumbledon’t, they cry. But that £500m fortune won’t add to itself.

As with the first Fantastic Beasts, one can’t fault the production design and period atmosphere – it’s a handsome franchise flick. The problem, once again, is that plot and character are far weaker in what Rowling imagines to be the looser medium of cinema, and consequently an hour’s worth of story is stretched out to 134 inattentive minutes – the sagging middle a slow travelogue peppered with humdrum setpieces. Does Rowling truly believe this is a five film series? Has success convinced her that any idea she has, no matter how underdeveloped, will be lapped up like milk from a magical teat? There’s a mystery at the heart of this film, but it’s not the identity of Ezra Miller’s non-descript wizard, or the sparing use of Depp’s Hitlerlarian sorcerer, rather why did Rowling think there was enough material to hang an entire second movie on?

She may be a children’s author, but she’s learned fast that the art of unwanted movie prequels is to defer the meat of your story to latter instalments, spreading your characters as thinly as possible. There’s an interesting nugget here, the parallel rise of wizarding fascism under a (it’s implied) charismatic leader, but his confusing pitch, that the wand brigade should embrace their own exceptionalism and assert dominion over non-magical folk before muggles with identical politics assert themselves and plunge the world into war, comes at the end of a long and meandering running time.

Depp’s plan to beat Hitler to the punch and blow up Paris, though understandable, only serves to highlight the film’s missed opportunity – to set the sequel in Weimar Germany, with the likes of Grindelwald inspired by the rise of Nazism, while using it as camouflage for his own activities. But perhaps Rowling reasoned this, despite the film being set in 1927, would be too explicit, too literal – far better to have the movie end in Depp’s version of the Berghof, and a promise that the next film will be based in, er, South America.

The real problem with The Crimes of Grindelwald is that it narrows the very universe it’s designed to exploit – sorry, expand. Once again we have a story built around exceptional children and special bloodlines – benign wizards versus would-be tyrants. Is it wise to keep telling kids that birth shapes destiny and inheritance acts as a straightjacket? It may be true, but if, like Rowling, you believe it shouldn’t be, why not promote the idea in your storytelling? It’s almost as if she dare not undermine the formula that made her. But nothing’s more likely to do that than a set of diluting and listless prequels.