Prince Of Darkness

With its themes of redemptive martyrdom and unholy apocalypse, not to mention the prime place it gives to an ancient text written by multiple authors in different languages, Prince Of Darkness seems to be positioning itself as a codicil to the New Testament – a sort of new gospel according to JC. Given, however, that those initials stand for John Carpenter, this is as radical a reinterpretation of Christian teachings as you are ever likely to find. Here the Church is merely a cover operation for a secret fraternity (situated, since the 1500s, in Los Angeles). Here Jesus was an alien, sent to earth to bring a warning that humans were not yet scientifically advanced enough to understand. Here Satan is a physical phenomenon at the subparticle level.

As Prince Of Darkness begins, a Catholic priest discovers an ancient, long-concealed artifact whose re-emergence appears to signify a new reign of evil on earth. This is not all that Carpenter's film has in common with The Exorcist (1973) – for soon we shall bear witness to possessed humans spewing green bile and a principal character taking a self-sacrificing plunge with the Devil.

Yet where it was the express intention of The Exorcist's director William Friedkin and its writer William Peter Blatty to terrify viewers back into god-fearing faith, Carpenter's altogether less orthodox aims are hinted at in his choice of pseudonym as screenwriter. 'Bernard Quatermass' is not just the film's credited writer, but also the name of the protagonist in one of Carpenter's favourite horrors, Roy Ward Baker's Quatermass And The Pit (1967), where, as here, an attempt is made to marry religion and science. All the demonology, zombies and portentous swarms of insects in Prince Of Darkness may point to conventional horror, but the quantum physics, time travel and multi-verse paradoxology ally it just as closely to the trappings of science fiction. It makes for a strange brew.

When an elderly priest dies, the key he is clutching leads Father Loomis (Donald Pleasance, retaining the surname of the character he played in Carpenter's Halloween) to a large crypt beneath the slumland Church of St Godard, where a sealed cylinder filled with mobile green fluid lies hidden. Learning from the dead priest's diary that the liquid, a form of pure evil long watched over by a secret sect known as the Brotherhood of Sleep, is now reawakening, Loomis turns for assistance to an old sparring partner, the theoretical physicist Professor Howard Birack (Victor Wong).

Amid sinister celestial activity and massing bugs, Birack gathers a team of his university's finest post-grads to move into the church and analyse the cylinder's increasingly active contents – but these young physicists, biochemists, radiologists and theologians quickly find themselves besieged on the outside (as in Carpenter's earlier Assault On Precinct 13) by hordes of zombie-like street folk (led by Alice Cooper whose song Prince Of Darkness also briefly features), and attacked on the inside by a fast-spreading demonic force that is looking to get out (in shades of Carpenter's remake of The Thing). Neither science nor religion is of much help – but at least the beleaguered survivors have both a 2000-year-old extra-terrestrial tome and a message from the future (transmitted in their dreams) to guide them towards humankind's only hope for salvation.

It is easy, along with its earliest critics, to dismiss Prince of Darkness as merely a series of cheap shocks glued together with preposterous expositional mumbo-jumbo (AND wooden acting) – but that is to overlook the serious bid that Carpenter's film makes for membership in the cinema of ideas. From its hero Brian (Jameson Parker) - first seen creepily ogling and stalking heroine Catherine (Lisa Blount) - to its portrait of a deceitful Church and a corrupted world, to its evil entrapped in a container that "can only be opened from the inside", the film suggests that we need look no further than into ourselves to see the workings of the devil – so no wonder, then, that it is through a mirror, that ultimate symbol of self-reflection, that Satan plans to launch his apocalyptic return.

With its well-paced build-up, its ominous soundtrack, and Carpenter's trademark handling of tension, Prince Of Darkness certainly earns its place on the margins of the horror canon - and no matter whether one regards the final sequence, much discussed on fanblogs, as chilling or hopeful, it remains devilishly ambiguous, ensuring that the film's interwoven strands of plotting keep coming back to haunt you – or, as Professor Birack puts it near the beginning: "Say goodbye to classical reality, because our logic collapses on the subatomic level into ghosts and shadows."

It is this boundary, at the outer reaches of the physical world where science meets superstition and reason collides with the irrational, that Prince Of Darkness so effectively crosses, telling a tale as miraculous as the Bible and as dry as any technical text.