This Is It and Imaginarium of Doctor Parnassus: a final communion Michael Jackson rehearsing for the cancelled O2 shows in a still from the movie

Film, Nic Roeg once remarked, is a time machine. We sit in the dark and watch people acting out scenarios that were recorded months or even years before. Sometimes, so it goes, these actors are no longer with us, and on these occasions we sit in the dark and conduct a relationship with dead people, like a bunch of frustrated, would-be necrophiliacs. At the Cannes film festival, the screenings are officially known as "seances".

Next month sees the release of Terry Gilliam's The Imaginarium of Doctor Parnassus and Michael Jackson's This Is It; two bits of unfinished business; two ghost stories for Halloween. The first casts Heath Ledger as an amnesiac drifter, except that the actor appears only fitfully and his death – midway through filming – has forced Gilliam to use other actors (Jude Law, Johnny Depp, Colin Farrell) to embroider the holes he left behind. This Is It, by contrast, gives us the rehearsals for an event that never happened: Michael Jackson's doomed 50-date tenure at the O2 Arena. I'd be willing to bet that, at some stage over the past few months, Dead Man Moonwalking was discussed as an alternative title.

Imaginarium and This Is It are obviously very different films, catering to very different audiences. Both, however, look destined to be remembered more for the story behind the movie than for the movie itself. Implicitly, perhaps even unknowingly, they invite us to look closely at Heath Ledger and Michael Jackson – studying each man for signs of impending death.

Of the two, Gilliam's film seems the less suspect, in that it is merely one of many ill-starred productions that found themselves hobbled by the death of their lead actor (a list that includes The Crow, Dark Blood and Plan Nine from Outer Space, in which Bela Lugosi dropped dead and was replaced by a chiropractor who looked nothing like Bela Lugosi).

But This Is It's pedigree is more dubious. Jackson's death was not a disaster for This Is It in the way that Ledger's was for Imaginarium. If anything it was quite the reverse. Jackson's death is the film's sole reason for being. Furthermore, preview clips, shrewdly drip-fed by the distributors, show us footage that one wonders if Jackson would ever have cleared: the sight of an exhausted man in the early stages of rehearsing a series of concerts he apparently had no wish to perform in the first place. No doubt there is something fascinating about all of this. Perhaps it even offers a valuable insight into the "creative process" or whatever you care to call it. That doesn't prevent it being a little sad, a little ghoulish; a bum trip aboard the time machine.

Source: Guardian Online