Secrets of the scariest film ever made
How The Exorcist used pea soup as vomit and gun shots to terrify the stars. By Guy Adams
A teenage girl, horrifically disfigured, sits up in bed and projectile-vomits dollops of thick, green gloop on to the face of a priest.
Then, in a stream of appalling profanity, the girl confirms what we already guessed: that she is possessed by the Devil.
As plot twists go, it's not exactly clever or sophisticated.
But the scene is hugely effective: this is, after all, one of the climactic moments of The Exorcist, which in turn is among the most terrifying and brilliantly-executed horror movies of all time.
Each year, as Hallowe'en approaches and Hollywood tries to bridge the gap between the summer and Christmas blockbuster seasons by making us scream, I'm reminded of director William Friedkin's 1973 masterpiece.
With its rotating heads and shaking beds, it's easy to dismiss it as crude and unsubtle; at times, it even teeters on the brink of self-parody.
But, when you watch it closely, you realise it's a hugely-accomplished piece of movie- making.
That's why it still puts the fear of God into people.
This week, a Blu-ray version comes out, containing not just all the usual digital remastering that accompanies expensive "collectors' editions", but also a fascinating new documentary based on behind-the-scenes footage taken from the sets in Georgetown and New York.
Shot on a wobbly hand-held camera, it has for 37 years laid undiscovered in the garage of Owen Roizman, the director of photography later shortlisted for the Best Cinematography Oscar (one of 10 nominations the movie garnered) for his work on its 10-month shoot.
Roizman's short film lays bare perhaps the two most important factors behind The Exorcist's success.
The first is, the extraordinary lengths to which Friedkin's technical staff went -- in an era long before the advent of CGI -- to achieve the extravagant special effects on which its narrative relies.
The second is the canny decision to give the production a pared-down, fly-on-the wall quality which would influence dozens of more recent horror hits, including The Blair Witch Project and Paranormal Activity.
Without either of those factors in play, the film, adapted from William Peter Blatty's novel, could very well have been an overblown disaster.
"This film was just begging to be a flop," is how Friedkin recently put it. "If we'd got it wrong, it could very easily have turned into a laugh-riot."
Instead, it was utterly convincing.
On a commercial level, the tale of Regan, a teenage girl who becomes possessed by Satan after playing with a ouija board, has made almost half a billion dollars for Warner Brothers, which originally backed it with a (then enormous) budget of $10m.
On an artistic one, it has come to define the career of Friedkin, an obsessive and often difficult individual who approached the making of The Exorcist in the manner of a mildly unhinged dictator.
The documentary tells how sometimes, just before cameras rolled, Friedkin would fire guns, so that his stars looked startled. At other times, he'd slap the actors across the face to make them appear angry.
Friedkin also required his entire set to be refrigerated, so that viewers would be able to see the breath of characters freeze during exorcism scenes.
"Today, doing that would be a piece of cake, right?" he says. "Today they can make you believe that the Titanic is sinking." Back then, it was a hugely expensive and uncomfortable operation.
You also learn how charmingly low-tech most of The Exorcist's other special effects were, and how remarkable it was that they still manage to look even slightly convincing on screen.
The famous scene when Regan's head rotates through 360 degrees, for example, was filmed using a life-size rubber model of the actress.
The model looks hopelessly artificial in broad daylight, but utterly convincing on a carefully-lit set.
For the scene where she vomits, an artificial device was strapped onto Blair's chin, and which used a hidden tube to fire a jet of green liquid, made by mixing of pea soup and porridge.
Today, most of Friedkin's other techniques also seem extraordinarily outmoded.
To shoot scenes at the angles he desired (in an era that predated "steadycam" devices), he required staff to erect a bewildering array of pulleys and wires, which the cameramen would simply be dangled from.
To make the bed, on which Regan sits for much of the second half of the film, rock violently, his crew installed a Heath Robinson-style mechanism powered by four men who stood backstage pumping levers. "Seeing what went on all those years ago has reminded me that this truly was, as we have been saying for so many years, the greatest magic act ever filmed," said Blair, who was just 13 when it was filmed, at the launch of the documentary in New York.
"What Billy Friedkin did on that set was magic. That's what I always tell people; there's simply no other way to describe it."
A great deal of The Exorcist's success also derives from Blair's remarkable performance.
One is struck by the patience with which she endured hours of uncomfortable make-up.
It's extraordinary watching how Blair would lark around until almost the moment the camera rolled, just how brilliantly she was able to turn her character on and off, and how superbly she was choreographed.
Today, Blair gives Friedkin huge credit for effectively gambling his professional reputation on a film that depended on the performance of small child. It required endless patience.
"Sometimes I wouldn't want to do something. And he would have to make it a game.
"Or he would offer me some sort of benefit. 'Would you like to have a chocolate shake?' he would ask. 'If you finish this then you can have one.'
"And it worked."
The Exorcist: Extended Director's Cut and Original Theatrical Version is out now on Blu-ray