Cheaper, trashier, perhaps even dumber films have been saved by the presence of Dwayne Johnson. So why is DC’s latest so doggedly immune to the redemptive power of the Rock? The key is in the secret ingredient: the priceless element that bestows unimaginable power on its owner. In this story, with its cobbled-together, disingenuously generic Middle Eastern backdrop, it’s allegedly a rare stone called Eternium. But in fact this is a red herring. The most valuable element, the one that unlocks Johnson’s considerable appeal, is rather more prosaic: humour. Give the man a couple of jokes and he works magic. Starve him of gags – as this loud, baffling screenplay does – and what’s left is stony-faced, gravel-voiced posturing.

Johnson plays an all-powerful entity called Teth-Adam, the saviour of the country of Kahdaq. But he has been interred in a sacred mountain for millennia; meanwhile, his country has been pillaged by invaders. Teth-Adam is reawakened by Adrianna (Sarah Shahi), apparently some kind of scholar, but who knows? The film doesn’t dignify her with much in the way of a backstory. Meanwhile, Viola Davis has dispatched the Justice Society to neutralise Adam. The ancient archaeological sites of Kahdaq take the brunt of it all.