I'd never heard of anti-matter before seeing this film (it exists apparently), but it didn't really make any difference. So many allusions, so many colourful explanations for this and that, so many little bits of knowledge are introduced, that the effect is like watching a bunch of characters on acid telling each other all about their weirdest dreams. Hanks and his sidekick, a gorgeous pouting Italian scientist (the Israeli actress Ayelet Zurer), have less than 24 hours to scour Rome in search of clues. So random and amateurish are their methods that they look more like a couple of over-enthusiastic participants in one of those weekend mystery tours. They rush from Sistine Chapel to Pantheon to Castel Sant'Angelo, filling in the blanks, making wild assumptions and at one point relying on the knowledge of a lowly tour guide to point them in the right direction (a moment which got a good round of laughter at our press screening). There is a twist of course, but for the even slightly awake it is easy to discern. Just keep an eye on the characters who seem to have no use to the plot from the outset. 

As a cross between Bond and Miss Marple, Hanks is an odd choice. He is an actor who majors in sentimentality and light comedy and has not a scintilla of credibility as a world-class academic. As the young Cardinal Camerlengo (the acting head of state of the Vatican during the election of a new Pope), Ewan McGregor glides through the film on a big fat pay cheque. But performances are not what films like this are about. Like airport novels, they are meant to provide rattling good yarns, of the kind in which the characters occasionally explain the plot to each other, just so that everybody can keep up.

Angels & Demons does have a couple of moments of suspense, which alone makes it a 100 per cent improvement on The Da Vinci Code. It also makes a half-hearted attempt at being more even-handed about the Church, by way of a brief, implausible speech by McGregor in which he suggests science and religion should be able to live in peace together. But this still leaves the question of quite how much damage Brown's oeuvre has done to Catholicism. I'm sure Catholicism is old enough and strong enough to take care of itself. But if I were a member of that Church, I think I would be furious at the way in which one cheapjack author of potboilers has managed to make a fortune by appealing to those who are equally ready to believe that the moon-landing was filmed in a Hollywood studio or that the late Queen Mother was in fact a giant lizard. Beware — such people walk among us.