Geopolitical relations between the U.S. and China may be dicey right now but now, in the spirit of cultural détente and big international box-office aspirations, Matt Damon and director Zhang Yimou have joined hands to make an epic fantasy film. Weighing in at a reported budget of $150 million U.S., The Great Wall has been touted as the costliest movie in China’s history, so it would be great to say that it’s also turned out to be one of the best. But it isn’t.

The Great Wall is a visual stunner, as can be expected from something shot by Stuart Dryburgh and Zhao Xiaoding and directed by the man who made the insanely beautiful Raise the Red Lantern and Hero. But this one’s a bloated, special-effects-heavy, supremely silly groaner, a leaden thing that’s almost wall-to-wall Lord of the Rings-influenced awful.

The movie stars Chinese box-office favorite Damon (looking dutiful and annoyed and occasionally attempting a something-or-other accent) and Pedro Pascal as comic relief, his Game of Thrones charisma ground down to zero. They play money-grubbing 12th century mercenaries of uncertain origin who, while scouring Northern China for precious black powder, get chased by bandits and eventually captured in the Gobi Desert by members of a highly specialized army of 100,000 called the Nameless Order. This vast Order, commandeered by a powerful general (Zhang Hanyu), has many arms and serves many functions but, for plot purposes, they’re best utilized as well-trained fighting machines against zillions of mythic lizard-type predators called Tao Tei, creatures that rise up like locusts from Jade Mountain every 60 years, growing bigger and shrewder each cycle. Their single aim? To decimate Chinese’s human population and destroy anything in their way.

The movie posits that the Ming dynasty’s 5,500-plus mile Great Wall was built to repel invaders that weren’t necessarily human—a premise that ought to sound familiar to many manga fans (Attack on Titan, anyone?). Once Damon and Pascal begin to figure out the basic workings of the Order, at least three big ole battle sequences erupt, each spectacularly staged and pulse-pounding and destined to provoke unfortunate comparisons to that big valley known as Helm’s Deep. As long as Yimou keeps the film as a whirligig of muddy motivations, thunderous music and whiplash editing, Damon and company are mostly in decent shape. But, come on: Even a slambang CG epic requires at least a pinch of character development and grabby dialogue.

Spouting anachronistic chatter (check out the dudespeak in Damon and Pascal’s bromance scenes or the head-scratching use of “I heard that!”) and finessing a script worked over by at least six credited writers, the naturally buoyant, smart-assed Damon is encased in medieval armor and a role that isn’t up his alley. Worse yet is Jing Tian as Lin Mae, an English-speaking commander of female bungee-jumping soldiers who has been conveniently tutored by a longtime detention-camp detainee (Willem Dafoe), who has also taught the language commander’s chief strategist (big star Andy Lau, given little of interest to do). It’s Tian who convinces Damon’s character that her nation’s people are not motivated by greed or the hope of fortune. She’s a lovely blank, especially when the script requires her to teach greedy Westerner Damon much-needed lessons in humility, faith and trust.

But no one’s at the top of their game here. After all, Damon’s coming off the Oscar-nominated smash The Martian and a not-terrible Jason Bourne, and Zhang Yimou directed Raise the Red Lantern, Hero and Curse of the Golden Flower, for the love of Mike. But even though The Great Wall has made over $219.2 million overseas alone, those plans for a franchise might need to be rethought.

The Great Wall