A live-fast, die-young generation, chasing around London, filling their lives with endless parties, fuelled by booze and other substances, piped by gossip columnists and paparazzi onto front pages for the delectation of a shocked public, spinning out of control… we’re in the 1930s, but it could be today. At least, that’s clearly the intention of comedian and polymath Stephen Fry, who has written and directed this adaptation of Evelyn Waugh’s rather more vividly entitled novel Vile Bodies.

Bright Young Things certainly starts with a bang, as we chase a paparazzo as he blags his way into a decadent country house party, takes a few illicit snaps of the fast set, and rapidly gets chased out. From then on our main point of entry is Adam (Stephen Campbell Moore), a well-connected but broke aspiring writer, whose search for enough money to marry his sweetheart Nina (Emily Mortimer) takes him on a series of picaresque adventures. But somehow the money remains tantalisingly out of reach, and reality begins to intrude on Adam and his friends, in the shape of mental breakdown, sodomy laws, and rumours of war…

On paper, this might seem like a drug-augmented episode of Jeeves & Wooster. And indeed, what with all the terribleh terribleh witty and brittle chaps and chapesses dropping sarcastic bon mots about how exquisitely bored they are, that is somewhat how it plays. Jeeves & Wooster was actually pretty good fun, in its own lightweight Sunday evening kind of way, but Fry is clearly aiming higher: he wants us to engage emotionally with his characters and their dilemmas, and it is on this level that the film slightly comes unstuck. The film is packed with comic characters and vignettes, many of them played by Fry’s famous friends turning up for a laugh, but many of these caricatures are so broad (and lumbering under such Dickensian names as Mrs Melrose Ape and Lottie Crump) that they jar somewhat with the rather more naturalistic style of the rest of the film.

It’s possible that none of this would matter if Fry had stuck with Waugh’s original ending, but he makes two major changes that take the film in a slightly different direction, and neither of them quite come off. The first two-thirds of the film is excellently paced, hotfooting it from party to dinner to racetrack and back. But when the film suddenly starts skipping years ahead, launching Adam into war, it becomes impossible to gauge what effect time and war is having on the characters – many of whom spin off or crash, never to be heard of again – nor how seriously we are supposed to take it all.

Secondly, while Waugh’s book ends unhappily on a battlefield, Fry clearly likes his characters, or at least Adam, too much to end without some kind of a resolution – in fact, let’s not be coy, without a happy ending. Which could have been fine – a downbeat ending might easily have been glib – but in practice it falls rather flat. The jolting shifts of tone have inevitably eroded our emotional investment, and Fry has to engineer Adam’s redemption at the expense of a minor character who, despite a sideline in war profiteering, isn’t really such a cad that he deserves the dismissal he receives.

But even if it doesn’t all come together, Bright Young Things is still vastly preferable to another of those tiresomely anaemic costume dramas that still perplexingly clutter our TV and cinema screens, and is certainly an improvement on the "Peter’s Friends with added flappers" that the posters suggest. Adam’s penury mitigates the Poor Little Rich Kid factor, and although those unfortunate enough to be neither young nor pretty nor well-connected are given pretty short shrift, the pace at which the film rattles along smoothes over the cracks. There is certainly enough of interest in here to suggest that Stephen Fry might yet have some pretty good films in him.