Warning: This review discusses the plot, including the film’s ending

Essentially there are two iterations of movie zombie, the George A. Romero swaying, snail-paced automaton that doesn’t pose a threat to anyone in reasonable shape and the infected of 28 Days Later; savage, fast, psychotic – predators you can believe in.

World War Z showcases the second. There’s a global conflict to deliver and human kind isn’t going to buckle from a pandemic of slow moving brain connoisseurs. The problem is that Marc Forster’s film is a summer tentpole with a blockbuster price tag. It must snap to fit a teen friendly rating – an obnoxious (and now all too common) example of demographics informing content. Consequently this sanitised pandemic can’t hope to offer the kind of brutality that Danny Boyle achieved in his Zombie reinvention. This is a shame because these are the kind of demented undead a World War requires.

Here they’re toned down lest they fall foul of the censor. They’re permitted to headbutt the odd window, like Hitchcock’s similarly out of control birds, they form unnatural ant-like towers, trying to breach walled defences, and advance in bug-like swarms but they’re never the visceral, violent threat that Boyle inflicted on the British. Given these constraints it might have been better if Forster had adopted Romero’s living dead. You could work with them on a bloodless takeover and you’d even have the option of substituting threat for satire.

Instead of frequent notes in the margin about how our much hyped civilisation, the envy of other planets, responds to being overwhelmed by ravenous monsters, we have UN troubleshooter Brad Pitt, never a hair out of place, circumnavigating the globe, looking for clues to a cure. The early portion of the film, set in Philadelphia but filmed in Glasgow to save on makeup and crowd control costs, annotates the slaughter with a few well-chosen asides; a beat cop more concerned for himself than arresting Pitt for murder, a hoody who hands over asthma medication for Brad’s sick daughter. The message is clear enough; as Rome burns you find out what people are made of and the best of us aren’t the ones you might expect, but that’s as close as we get to any account of the war’s social impact. The rest is an inanimate, sometimes subdued Pitt on his travels, running from the diseased hoards. It’s a non-stimulating investigation that threatens to turn World War Z into World War Zzzzzzzzz.

Forster’s got a good eye and gives a sense of scale to proceedings, particularly in Jerusalem, where the crazed infected are photographed from above, bug-like, but he can’t deliver original thrills. We’ve seen this or something like it so many times before that any sense of shock immediately dissipates. Despite its $200m price tag, the very thing that might have made it distinctive – grand, set piece Zombie attacks – is lacking, particularly in a low-key and underwhelming third act set in, and I’m not making this up, a Welsh health clinic (an act reshot in its entirety, making the original more of a curiosity than the film itself). Consequently a film that cost about as much to produce as Man of Steel culminates in Brad Pitt walking along a corridor, having broken a vending machine. It’s a heart stopping denouement that’s words can’t adequately convey.

Had Brad’s investigation being more labyrinthine, more complicated, perhaps this would have been a genuine fresh twist on a well-worn genre. Instead Pitt makes progress based upon a couple of conversations and some lucky observations. There’s no sense he’s had to work particularly hard to yield this information, nor that he required a special skill set to do it. In fact, our suspicions that Pitt’s nous is wanting are confirmed more than once – he gets drops of Zombie blood in his mouth, doesn’t turn but doesn’t think to report it in case it may be medically significant; he’s so desperate to kill Zombies that he throws a grenade on a aircraft, causing it to crash, but having survived that it doesn’t occur to him to kill the Zombie that also survived. Is this man truly our best hope or have the better UN investigators been killed? It’s a question neither asked nor answered.

As Pitt’s quest runs its course we’re reminded that disease flicks needn’t be derivative or uninspired. David Morse features as a toothless traitor in a South Korean holding cell. Once upon a time Morse and Pitt were suspects in another global pandemic, the viral genocide of 12 Monkeys. Visual imagination, intrigue, a surprising conclusion – we were doomed yet entertained. There was even a grab bag of jokes in that apocalypse. Those were the dying days.