Trailer for forthcoming film The Dark Knight

As the obituaries roll out, the film most often invoked as a measure of Heath Ledger's skills as an actor is Brokeback Mountain (2005). And certainly Ang Lee's movie about a couple of ill-starred gay ranch-hands brought him deserved worldwide acclaim and an Oscar nomination.

But when I think of how good he was, and how good he might have been, I think of a lesser-known work, Candy, which was released a year later. It was a small, independent film made by a relative unknown called Neil Armfield and starred Abbie Cornish and Ledger as a pair of besotted heroin addicts whose love affair proves as destructive and tragic as the drug on which they are hooked.

The resonance with the reports swirling around Ledger's final hours is all too melancholic and clear. The trajectory of the film is numbingly predictable, but the graphic chemistry is terrifically sensual. For Ledger it was a joy and a relief to be able to do this tough role in his native Australian accent, despite the fact that his paycheque could be counted in beans. Few of his far-flung fans appreciate how isolated prolific actors sometimes feel when they are forced to part from their native drawl.

Cornish was one of the very few actresses to work with Ledger on such a psychologically demanding project. “He isn't just another actor. He has always been a very specific and creative artist,” she told me. “As draining as this film was, it was easy walking into the make-up bus knowing I was going to spend the entire day with him. Working with Heath pushed me to new places.” Candy revealed a taste for the dark side that many of Ledger's professional admirers may not have credited him with before.

His sudden death is a profound shock, one of those rare aberrations in Hollywood in which a bright young actor's life (James Dean, River Phoenix) is stubbed out far too early. Rock stars have precarious lifestyles and exotic addictions, sure. It's in their DNA. But how does a tragedy such as this befall a supposedly healthy workaholic with a number of prolific films in the pipeline? Reports suggest he had suffered a substance abuse problem, but the manner of his death still seems utterly out of sync with what we know of Ledger's personality.

Hollywood has lost him at the moment he was, if not at the peak of his powers, then certainly way into the ascent. How the studios intend to market his last, as yet unreleased, screen performances will be a source of heated debate. One of the films at stake is the new multimillion-pound Batman instalment, The Dark Knight , in which Ledger plays the Joker opposite Christian Bale's caped crusader. Christopher Nolan's film is now finished and is due to dazzle the world in the summer. Yesterday Warner Brothers said the release date (July 25) was still in place; how they will market the movie (early reports say Ledger's Joker is definitive) is another matter.

Last week Ledger was in London working on Terry Gilliam's The Imaginarium of Doctor Parnassus. At the time of writing, representatives for Gilliam said they had no comment to make on the film's release, or Gilliam's feelings at the loss of Ledger.

He was last seen in Todd Haynes's extraordinary homage to Bob Dylan, I'm Not There. Ledger played one of the seven incarnations of Dylan: a butch motorcycling troubadour who has his hands full trying to keep Charlotte Gainsbourg happy.

How to give an inkling of the loss? His solid commitment to films and scripts that he believed in gave him kudos among his peers. He was also a humble heart-throb, managing to defy the poster-boy image that first dogged him.

The 28-year-old was born in Perth, Western Australia. He left school at 17, hitched to Sydney with barely a dollar in loose change in his pocket and got his first real break in a low-budget film called Blackrock (1997). A part in 10 Things I Hate About You (1999) put him on the map. He won plaudits for a cameo in Monster's Ball (2001), and revealed an unexpected talent for comedy in A Knight's Tale (2001).

He could have played the beefcake, the heart-throb, over and over again: he was startlingly handsome with playful eyes and a broad-shouldered swagger. But he didn't.

Reviewing his CV you realise it is littered with curios, parts he obviously took on for love or just the challenge, perhaps most notably his turn as Jacob Grimm in Gilliam's wonderfully bizarre homage to The Brothers Grimm.

Gilliam, who turned out to be his last director, recognised instantly that he had a singular talent in his grasp. Unfortunately that precious talent has been extinguished far, far too early. The frustration is that he would have gone so much farther in roles we will now never see.

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