It may still be the depths of summer, but the (very British) adaptation of a (very British) classic novel set in the costume- and set-designer friendly 1930s positively shrieks "Oscarbait!" from the highest rafters, and by all means, the new version of Evelyn Waugh's Brideshead Revisited is a perfect exemplar of the form: it's been fussed over until there's not an inch of life left in the thing, just the glassy pleasures of an instant museum piece; but good God, it's easy on the eyes - without question, the most visually appealing film in the career of its resolutely impersonal director Julian Jarrold (whose last assault on literature was the speculative Jane Austen biopic Becoming Jane).

I speak advisedly, having never read Waugh's novel nor seen the celebrated 1981 Granada TV miniseries, but it's quite obvious that the story has been shred to ribbons in its transition to a two-and-a-quarter hour script, adapted by Andrew Davies and Jeremy Brock. What remains is essentially the Cliffs Notes version of a narrative detailing how poor artist Charles Ryder (Matthew Goode) befriends the charming gay aristocrat Lord Sebastian Flyte (Ben Whishaw), and accompanies him to his ancestral home of Brideshead; there, Charles transfers his affections from the increasingly needy Sebastian to his aloof sister Julia (Hayley Atwell), and generally lusts after the glitzy life of the idle rich in Britain prior to World War II. This all takes place over the course of some years, although just how long is up for grabs; the beginning hops from place to place without much context, while the ending unravels in a Greatest Hits-style chain reaction of plot points. At any rate, the latest scenes are about 10.5 years after the earliest.

But muddying up what happens when isn't really as big a sin as leaving unanswered and mostly unexplored the question of why. The point of all this is that Charles is seduced by the glamour and sex of Brideshead, but other than clunky dialogue stating that outright, it's not a theme that the film seems particularly able to address. In fairness, that's probably not a writing issue nearly so much as it is an acting issue: neither Goode (best known for playing essentially the inverse of his present character in Match Point) nor Whishaw (who played the underwritten lead in Perfume) have enough range to balance the fluid motivations required to make their characters sensible. Goode is just too damn uncharismatic for it to be remotely plausible that he can seduce the whole Flyte family as quickly as he does, while Whishaw is stuck in petulant mode for most of the film, at those times when he isn't busy reducing Sebastian to a swishy gay stereotype. As for Atwell, it's hard to say if she's a dynamic performer - her most prominent role was as window-dressing in Cassandra's Dream - but she lacks whatever spark is needed to bring much of anything to Julia, easily the most poorly-written character in the film.

However, Goode, Whishaw and Atwell all have one thing in common going for them: they are all quite pretty. Which fits them nicely into Brideshead Revisted, which for all its conspicuous and considerable narrative sins is a deliciously sensual movie. When you set a movie amongst the British upper classes, especially before the middle of the 20th Century, you've pretty much guaranteed that the costumes and sets are going to be wonderfully decadent, and at least as eye-candy, the film does not disappoint. As filmed at Castle Howard in Yorkshire, Brideshead is every bit as lovely as it would need to be to inspire Charles's instant lust; I'd love to meet the person who wouldn't sell out an ideal or two for a shot at life in a house that damn big. I must admit to having one complaint about the visuals: the movie is shot in surprisingly low light. It almost seems that cinematographer Jess Hall got it in his mind to shoot this period piece as a film noir, which although an adventuresome idea, isn't one that pays many dividends in the end.

Leaving us with but one thing to consider: Emma Thompson. As the cold matriarch of Brideshead, Lady Marchmain, Thompson's performance absolutely ranks above the best of her career, and even though her character is not onscreen for such a great deal of time, she absolutely dominates the film (I'm reminded of a time not so long ago, when Thompson was far and away the best element of the middling Love Actually). The actress doesn't just disappear into the role; she positively disintegrates, so much that I was honestly a bit rattled when her name popped up in the closing credits. Latching on to the fundamentalist Catholicism that passes for love in Lady Marchmain's eyes, and radiating hateful indifference with naught but a mild sneer and a raised brow, Thompson is a brilliant, overpowering villain; too strong for the meandering script that contains her and infinitely too strong for the twerpy Goode to stand his ground against.

So it's not that Brideshead Revisited is a pointless film; more that it is a dry run for a film that does have a point. It's not even a film without ambition, trying to be all intellectual for grown-up audiences in the summer, but it's just not that good at it. At least there's part of a good movie here, and at least it's the pretty part.