Big Fish (PG)

Tim Burton (125 mins), Starring Ewan McGregor, Albert Finney, Billy Crudup

The typical Tim Burton hero is a ball of neurosis with a passing resemblance to a human being. The tension in Burton's movies comes from the disparity between the internal lives of fragile man-children like Bruce Wayne (in Batman) and Edward Scissorhands, and the hostile environments that refuse to accept them. His latest film, Big Fish, represents the first time that these interior and exterior worlds have been happily reconciled. This would be an advancement if the picture had access to an alternative source of conflict. But Big Fish isn't concerned with moving on: it's about summing up, taking stock. Not for nothing do these terms have about them the ring of the audit or inventory.

The film is mostly comprised of fanciful stories spun by Edward Bloom, an Alabama dreamer of varied occupations: freedom fighter, financial adviser, unwitting bank robber, travelling salesman of novelty robotic hands. Edward's sceptical son, Will (Billy Crudup), remarks in his voiceover that in telling his father's story it will be hard to separate fact from fiction. What the audience is likely to deduce long before Will does is that Edward's extravagant narratives are more revealing than any biographical details.

As a storyteller, Edward comes across as strong on incident but poor on characterisation. For example, when he recounts his courtship with Will's mother, Sandra (played first by Alison Lohman, then Jessica Lange), the tale balloons into a Fellini-esque fantasia involving a circus apprenticeship, a werewolf, and the freezing of time. At no point is it made clear who Sandra is, or why she is special, unless you count her ability to make the lens come over all soft-focus.

That can be blamed on the screenwriter, John August, who has adapted Daniel Wallace's novel. August doesn't know how to keep his female characters occupied, which is a switch from his scripts for the Charlie's Angels films, where women had no shortage of things to do, none of which involved household chores. Will complains of being a footnote in his father's story, but he should be thankful; his own wife and mother are footnotes to a footnote. When a significant scene is approaching, the women decide to wash the dishes. When Edward is in hospital after suffering a stroke, Will sends them home to do whatever it is that women do while fathers and sons make up for lost time.

Edward is played by Ewan McGregor in the flashback passages that run from the 1950s to the 1970s, and by Albert Finney in the present-day scenes, which are largely confined to Edward's deathbed. It seems initially that Crudup has picked the short straw in the casting room, since McGregor is at the heart of the movie's liveliest scenes, while Finney gets to be so demonstrative in the fangs of mortality that you expect a doctor to turn up and tell the family: "The prognosis isn't good. The best we can hope for is a nomination for Best Supporting Actor."

Gradually, though, it becomes apparent that this is Crudup's film. It could be that his bone structure - that jaw on which you could crack open a bottle of beer, those cheekbones like mantelpieces - is the one element of the picture that has definition. Certainly, his is the only role that covers any emotional distance, even if it's just a last-minute dash from bad-tempered doubt to serene certainty. Conversely, McGregor doesn't have to do more than respond blithely to whatever the plot throws at him, whether it's a glamorous pair of conjoined twins or a giant with a brow like a Buick. And if Finney is rewarded for his performance, it will be one of those prizes, like the Oscar that went to James Coburn in 1999, which congratulates the recipient on not being dead yet.

Finney's voice, which sounds like it was dredged up from the bed of the Styx, can put an authoritative rumble into the weakest line, but the film diminishes him in its hunt for pathos; a formidable actor is reduced to little more than a pair of twinkling eyes.

Strangely for a director who has specialised in pinpointing the overlap between dreams and nightmares, Burton finds little darkness in the world of Big Fish. There is at first a sinister edge to the magical town of Spectre, into which Edward stumbles after becoming lost in the woods; those inhabitants that haven't wandered out of Village of the Damned are evidently related to the banjo player from Deliverance. But by the time Edward has returned to Spectre to restore its former prosperity, this ambiguity has vanished into the ether, or into the editor's bin.

It is possible to make a durable fantasy with no villains - it was precisely this achievement that François Truffaut admired about Close Encounters of the Third Kind. But without a robust vision to sustain Big Fish, the absence of tension creates a curiously passive environment in which the audience must work to harvest the tiniest crumbs of stimulation. Burton still knows how to contradict an image of innocence without quite corrupting it, such as when Edward is beaten black and blue against a background of blazing yellow daffodils, or when a clown opens a compartment in the front of his costume to reveal a pistol mounted in red velvet. And the danger posed by desire is as immediate here as it was in Batman, Edward Scissorhands or Pee-wee's Big Adventure: a man has a fatal heart attack while reading Playboy; a milkman who has been sleeping with one of his customers drops dead on her doorstep.

Where there is not disdain for sex, there is indifference: the camera is no more enamoured of a mysterious nude who does laps of the lagoon than it is of Danny DeVito's buttocks in close-up. Big Fish may be the closest Burton gets to Wild Strawberries, though that still isn't especially close. More likely, it will transpire to be his own Adventures of Baron Munchausen - another compendium of tall tales that never hangs together. It's the comparison with a different Terry Gilliam film, though, which demonstrates that Burton lacks the control to reel in his Big Fish. In Time Bandits, the revelation that what has seemed to be a dream is in fact reality is conveyed in a single conspiratorial wink witnessed by the young hero. In Burton's movie, a similar guarantee of authenticity is provided by a lengthy flashback, a symbolic baptism and an epic funeral, all shot by a camera that swoops and soars so frequently it might have been hitched to a passing heron.