For one of the most famous men in modern history, Bob Dylan has constantly defied easy classification. A shape-shifter and a master of inventing new personas for himself, Dylan is a mythical, often contradictory, figure about whom much has been written but very little is known.

Over his 40-year-plus career, there have been several 'Dylans' - the protestor, the 'voice of a generation', the Judas, the rock 'n' roll Dylan, the born-again Christian, the divorcee and the self-exiled musician.

So enigmatic and revered a figure is he, Dylan's life would seem ripe for a 'Walk the Line'-style music biopic were it not for the fact that his story is so complex and so shrouded in myth and secrecy. Where would you start? How long would you have? How would you distinguish the truth from the myth?

Step forward then Todd Haynes, whose clever and crazy approach to the biopic concept has resulted in an entertaining, rewarding sweep through Dylan's past, and made for one of the year's finest movies.

Haynes' approach is this: six actors play seven different 'Dylans'. One of the actors is a woman, another is a black child. None of the 'Dylans' are actually called 'Dylan'. In fact, the name 'Bob Dylan' is not mentioned once over the movie's 135 minutes. Instead we get Robbie (Ledger), Jack (Bale), Pastor John (Bale), Jude (Blanchett), Woody (Franklin), Billy (Gere) and Arthur (Whishaw). 

The film is told like a jigsaw as actors and scenes swing in and swing out, moving backwards and forwards in time through colour and black and white, all the while soundtracked by choice Dylan classics.

One minute you're watching Cate Blanchett as a frenzied version of Dylan juggling praise and disdain for not playing the role expected of him then, in a blink, we're with Christian Bale as the early 1960s folk star before hovering back to Dylan imagined as a precocious 11-year-old rambler.

Pieces of fact are interwoven with flashes of fiction with Haynes taking licence to mould Dylan's past with what best suits his haphazard plot - and the plot is haphazard.

The 'seven lives of Dylan' begin with Woody (Franklin), the aforementioned 11-year-old, wise beyond his years and reminiscent of Twain's Huckleberry Finn. With a nod to Robert Johnson and Woody Guthrie, here the formative Dylan is vaguely outlined.

In between we hear from a second Dylan, 'Arthur Rimbaud' (Whishaw), all complex and poetic swirling statements, before the 1960s folk scene and Jack Rollins (Bale) are recalled in a mock-documentary which sees the audience looking at a film about Dylan showing a documentary about a 'Dylan-like figure'. Here Haynes takes in the emerging Greenwich Village folk scene and Dylan's relationship with Joan Baez.

The movie then jumps to rising actor Robbie Clark (Ledger) whose romance with Claire (Gainsbourg) touches on 'The Freewheelin Bob Dylan' and Dylan's break-up with Sara Lownds as 'Simple Twist of Fate' and 'Idiot Wind' from 'Blood on the Tracks' linger in the background.

Arguably the most famous version of Dylan - the skinny, Ray-Ban clad, wild haired and wicked tempered 'electric Dylan', circa 'Like a Rolling Stone' - is played by Cate Blanchett in what is one of the decade's most remarkable performances. Blanchett simply seems to become Dylan, managing to make perfect sense of Haynes' decision to cast a female actress in a male role.

The 'Dylans' are then capped off by a trip to the Wild West and outlaw Billy (Gere) in what is perhaps the most warped and heaviest section of Haynes' movie. Here, though, the director's central point is emphasised: the key to Dylan's character is a constant need to challenge what is expected of him and to fight any form of authority.

The great man's music understandably plays a key part in the movie with Haynes carefully selecting tracks to complement each section of his tale. To fully appreciate this aspect of the film, an understanding of Dylan's work and past is mandatory.

Indeed, throughout, Haynes assumes that the film will find an intelligent audience clued up on the subject matter. In this regard those who know little of Dylan's work may feel lost and will end up leaving 'I'm Not There' more confused than when they entered. This is not a movie by which to learn more about Dylan's life. If anything, Haynes crafts his film in a manner which leaves us nowhere nearer to understanding the man himself. This is the whole point.

In all, 'I'm Not There' is a clever and inventive movie and one which remains closely aligned to its subject matter -  constantly moving, impossible to pin down and all the while reinventing itself under a new guise. Highly recommended.

Steve Cummins