I haven't read the four novels written by Kyril Bonfiglioli in the 1970s that feature the adventures of Charlie Mortdecai, an aristocratic art dealer, but I'd rather like to do so. This is an abomination of an adaptation, yet another vehicle for yet another Johnny Depp caricature, but at its heart is a story I wouldn't mind seeing done right. At this point, that surely means going back to Bonfiglioli because screenwriter Eric Aronson either doesn't understand what he's trying to do or, more likely, he does and the results are cringeworthy.

There's a mystery afoot, but before it gets properly moving, we're thrown a whole collection of English archetypes, of the sort that are sent up with so much dry humour in the Ealing comedies but which are handled with ham fists here. To be fair, some of the dialogue is written very well indeed, but it's rarely delivered as it should be. Imagine Alec Guinness or Dennis Price speaking it and it would sound much better. More pointedly, this moves quickly from the unpleasant to the outright crass and that's unbecoming for the material.

We begin, as we might expect, with the aristocracy, Charlie eight million pounds in debt but still walking with a cane, driving a Rolls and living in a country mansion. He has the requisite manservant, Jock, as relentlessly capable as all manservants apparently are. The key characters work through every traditional English characteristic they can find, from dry understatements to polite oneupmanship, from the stiff upper lip to rogering the farmer's daughter, from outwitting the constabulary to cultivating a set of moustaches.

This actually could have been fun. Paul Bettany is spot on as Jock, the latest in a long line of such characters. He plays the part straight, if a little more down to earth than usual, and he's very enjoyable. Charlie's wife, Johanna, is played by Gwyneth Paltrow, who is also decent, especially early on. Certainly the first time we find ourselves really enjoying that dialogue is from her lips, as she spars verbally with Inspector Martland, a strong but almost unrecognisable Ewan McGregor.

Unfortunately we also have the title character to deal with and Martland soon brings him into the mystery at the heart of the script, all about a legendary painting by Goya that once found its way into the hands of Herman Goehring, who wrote the codes to his Swiss bank account on the back of it. Bronwen Fellworthy, who was cleaning it for person or persons unknown, is murdered and the painting stolen, so Scotland Yard come to Mortdecai for help. As the thief promptly lost it to another thief, confusion abounds as to where the painting is and who has it and Mortdecai naturally finds himself at the heart of the chase.

At one point, at the scene of Bronwen's murder, Martland asks Mortdecai, 'Are you quite finished buggering around?' 'No,' he replies and he isn't kidding. Unfortunately we're never quite sure if the response comes from Charlie Mortdecai or Johnny Depp.

Certainly it's Depp who, more than anyone else, destroys what this film could have been, because his take on Mortdecai is wrong in every respect. It's not merely that he's not taking the role seriously, playing another clown lead with a set of straight men to bounce off. It's also that the parody isn't either funny or pertinent, merely annoying and out of place, if not outright racist. Charlie Mortdecai is just the latest in a sadly growing line of his overdone cartoon characters. It's certainly worse than his Mad Hatter; right now, while I'm still reeling from it, I'd suggest that it's worse than his Tonto and his Barnabas Collins too, but that feeling may fade over time.

Unfortunately, the more the film runs on the more the other actors start to follow Depp's lead. Early supporting actors attempt to do their thing in spite of him, but later ones actively help him to derail the picture. Jeff Goldblum is a rich American who apparently wants nothing more than to look like Groucho Marx and Jonny Pasvolsky portrays Emil Strago, art thief, just like Kevin Kline in 'A Fish Called Wanda', except without the fun, while Olivia Munn is suitably sexy but a one note character to be wasted. Even Bettany, playing Jock like Jason Statham as Jeeves, is stuck with idiotic character progressions so he gets worse in spite of himself.

I really don't know whether the balance of blame should fall on those actors or the script they're forced to enact. We're subjected to scenes of sex and vomit, fortunately never at the same time, not to mention a fetish for testicular torture and double entendres unbefitting even a 'Carry On' movie. It's as if Aronson isn't sure if he wants to make a screwball comedy, a caper flick or just a parody of something or other.

I'm leaning towards Aronson as the key culprit, but director David Koepp can't escape blame either. The camerawork is just as blatant as the script, with only the transitions between places interesting; the continuity is like a Saturday morning cartoon and the score is astoundingly unimaginative. Put it all together and the lack of any cohesive vision can't help. No wonder its $60m budget was matched by only half that in box office receipts, making this a notable flop.

The sad thing is that I left the picture wanting to read the original story, not because I enjoyed this adaptation of it but because I want to see how outrageously it was mangled and whether there was really substance there to begin with. ~~ Hal C F Astell