After Paul Schrader had filmed Dominion: Prequel To The Exorcist, the studio took it away from him - because his psychological horror was not the gore-fest they'd wanted - and handed over the reins to Cliffhanger's Renny Harlin.
The film underwent a major rewrite, some recasting and an almost total reshoot and emerged on the silver screen as Exorcist: The Beginning in 2004.
Schrader's version - although highly anticipated (this was the man who wrote Taxi Driver after all) went unseen until all the Exorcist films were released together on DVD in the early 2000s.
Unfortunately, I'm not sure if the wait was worth it. Dominion is very rough round the edges, and while it builds slowly (like the original Exorcist - but totally devoid of the genuine fear that film still invokes after all these years) and the threat level is allowed to gradually develop as the madness of the demon Pazazu spreads out from its hiding place, nothing very substantial actually ever materialises.
And the "suddenly everything is better" ending is shameful.
Both films follow a young Father Merrin (Stellan Skarsgaard), who has left the church to pursue his passion for archaeology after a crisis of faith during the Second World War.
In 1947 East Africa he investigates a mysterious, perfectly preserved, buried church... and what lies beneath.
But where Dominion goes for discreet imagery and symbolism, Exorcist: The Beginning relies on in-your-face shocks and a gruesome body count. Merrin in this film is more a shotgun-wielding, babe-snogging, tomb-robbing Indiana Jones than the conflicted priest of the earlier iteration.
The film's main female character - a doctor - changes from the 'average/normal' looking woman of Dominion into the Swedish beauty of the second (as Harlin says in the 'making of' doc: "You don't go to the cinema to see everyday people").
The African natives, who play a smaller role in the The Beginning, have also learned to speak perfect English. The language-barrier was something that Schrader had used in his version to emphasise the differences and rising tensions between the locals and the British Army occupiers.
Pazuzu itself, once it appears, has also been transformed from a floating baldy guy into a gravely-voiced, Buffyesque, butt-kicking monster with direct visual lifts from the original (something sorely lacking in Schrader's version).
Harlin's film also cherrypicks from other horror classics, for instance we get the flys from The Amityville Horror and mad priests and menacing dogs (in this case, hyenas) from The Omen.
This is The Exorcist for the Nightmare on Elm Street/Friday 13th generation, who don't like their horror to test their brains too much; but 'sadly' it's still a more exciting movie than Schrader's insubstantial meditation on the nature of evil.