Harrison Ford (old), Shia LaBeouf (greasy), Karen Allen (mumsy), Cate Blanchett (bobbed), Ray Winstone (Ray Winstoney)

Background: Close to twenty years, it took. Nearly two full decades, apparently, to perfect a script. To gather its peerless troupe of main players, to synchronise impossibly busy schedules and to hone a suitably astonishing final chapter to one of the greatest film franchises ever. Then 79 filming days to commit a genuine world cinematic event to celluloid: the fourth Indiana Jones movie. And what do we get? We’ll tell you. CGI gophers with surprised expressions, that’s what. Infantile, clunking dialogue. Green-screen sub-XBox action sequences. Elderly people kissing. The only human being ever to survive a nuclear detonation at point-blank range. Later, CGI monkeys with expressions. And your worst nightmares confirmed – aliens and flying saucers. Yes, it’s worse than you could possibly comprehend. A more stultifying disappointment, arguably, than The Phantom Menace. Maybe we’re still reeling, but it might even out-shit The Star Wars Christmas Special.

Bear in mind exactly who worked on this movie. Not just a reunion of “the safest hands in Hollywood”, but backed up by story input from the likes of M. Night Shyamalan (The Sixth Sense), Tom Stoppard (Shakespeare In Love) and Frank Darabont (The Shawshank Redemption). Even final script duties went to David Koepp - perfectly capable, as Spider-Man 1 and 2 confirmed. And yet here he’s flailing wildly out of his depth, proffering a script lacking in ingenuity, style or life.

The story: It’s telling that the plot needs little extra exposition than reading the title itself. Indiana Jones, now a tenured professor, is tasked with finding a crystal skull. And that’s pretty much it. He’s partnered by young biker Mutt (LaBeouf) and former Raiders squeeze Marion Ravenwood (Allen), and the Nazis have been replaced by the Russians, lead by psychic dominatrix Spalko (Blanchett). But otherwise it’s mysteriously linear. Re-framing Indy as a decorated war hero post-WW2 indulges Hollywood’s greatest obsession, 1950s Eisenhower America. And veteran cinematographer Janusz Kaminski captures the milkshake-and-varsity-jacket gloss of that era perfectly. But with the majority of scenes completed on garish sets or green-screen CGI, it feels more like an episode of The Crystal Maze with the colour turned up. Indeed: pausing it on DVD may yet yield a grinning Richard O’Brien, bouncing out of background shrubbery playing a harmonica.

Whose fault is it? Blame for this can only rest with Spielberg. George Lucas has already reserved his deckchair in cinematic Hades, so it should be no surprise to spot his ham-fisted “signature touches” (e.g. the aforementioned gophers) throughout. But it’s Spielberg who’s let go of the reins. From the director of Schindler’s List, Munich and Saving Private Ryan comes a lazy two-hour hotchpotch of pedestrian pacing, disjointed narrative and – aside from possibly the very opening shot – criminally little invention. Even the basics are lacking. Scenes die in poor framing. Dialogue fluffs in the audio mix. Rare one-liners fade in ponderous editing. And action sequences choke under overwrought CGI, despite his interview promises to return to “rudimentary film-making”. The cast offer little help either. Harrison Ford can still take a punch, and there are brief glimmers of former enthusiasm. But every one of his 65 years are onscreen: he huffs, wheezes, staggers like your dad, and has entirely forgotten how to flirt with Karen Allen. Around him, Blanchett struggles with her ’Allo ‘Allo accent and Winstone phones in his gruff SAS turncoat Mac - heading a supporting cast seemingly satisfied to just smirk and high-five their old billionaire mates. Only LaBeouf, to be fair, emerges with his everyman dignity intact. Oh, and maybe the janitor from Scrubs.

The good bits: It’s not entirely bad. The first reel’s warehouse scene is old-school fun (although you’ve seen the highlights in the trailer), as is the early motorcycle chase. Taken as a stand-alone film, purely its own merits, it might scrape three stars. But there’s a heritage here being slowly eroded before your eyes.

The bad bits: In paying homage to the first films with blunt-force “nods”, they force a re-evaluation of the old trilogy. For instance, in Last Crusade, the “stupid bit”– i.e. the part requiring the most devoted suspension of disbelief – was to trust that a 500-year-old man could live alone in a cave. So brace yourselves: in Indy IV, there are 13 of them. The stupid bit in Temple Of Doom was Indy’s shrill, desperate fall out of a plane onto the Himalayas in a dinghy. In Indy IV, something equally implausible happens three times. And even in the sacrosanct Raiders, we forced ourselves to believe that ancient civilizations had built intricate keepsafes and booby traps that still functioned centuries later. In Indy IV, we… well, we defy you to watch the final 45-minutes without at some point opening your mouth and cuss words coming out. The worst kind of cuss words. And worse, it was all salvageable. The opportunity was there: all we needed was a moment of danger, of hopelessness, of insurmountable odds. And then Ford could set his jaw, find new inner strength, climb up the ladder/rope/submarine and John Williams could start parping his signature anthem again.

But no. Suddenly, he’s impervious. There’s no ceiling spikes, no rolling boulders, no having his face rubbed on a wall by a tank. Instead, we get a cringing wedding, an insulting vine-swinging interlude and countless other affronts to our childhoods. And he only uses his whip twice. We wanted so hard to like this. Remember that this wasn’t pitched as “one for the kids” like the Star Wars prequels. Time and time again it was promised to “the fans” – a movie they’d wait years to perfect before embarking upon it. We looked at the list of working titles - ‘The Destroyer of Worlds’, ‘The Lost City of Gold’, ‘The Quest for the Covenant’ – and hoped for the best. Then we heeded early reviews and prepared for the worst. But nothing equipped us for the end result: an entirely pointless, will-this-do sequel to a trilogy that should have ended on a ride into the sunset two decades ago. And when even this assembled talent – riding such collective worldwide enthusiasm – so utterly fail to produce even an occasional spark of delight or creativity, what’s left for everyone else?

CGI gophers. Think about it.

More: For the FHM's I-Spy list of glaring plot holes, click here.