"Hello? I'm opening the door, if you want to stop what you're doing and put your clothes on!"
(Spoilers.) Another one of those films that is hard to either hate or to like because there are so many reasons to do both.
After a slew of high-budget flops, Carpenter returned to his low-budget roots for this bodycount horror film that liberally steals aspects from films as diverse as Five Million Years to Earth (1968 / trailer) and Demons (1985 / trailer), not to mention countless other zombie and kill-by-number movies. (That Carpenter owes something to Five Million Years to Earth is underscored by the fact that he credits the movie's script to "Martin Quatermass," a direct reference to the main character of the Hammer film and the English television series it was based on.) Peppered with all sorts of quantum physics and religious mumbo-jumbo and featuring a flawed narrative from beginning to end (not to mention a group of unlikable non-characters with horrible 80s blow-dried haircuts), what works the best in this film is its low-budget atmosphere and the cheap tension that mounts as the next would-be victim approaches his or her unavoidable doom.
Featuring what may be the longest opening credits sequence in the history of films, The Prince of Darkness also features one of the few times in which Carpenter's music actually helps build tension. True, it is basically the exact same dirge that he has used in every other horror or science fiction film that he has yet made and scored, but for some unexplainable reason it doesn't annoy as much as normal.
In one way, The Prince of Darkness is almost the flipside of They Live! (1988 / trailer), Carpenter's project the next year, another film which also featured a large amount of homeless people. Unlike They Live!, however, in which the homeless are good people repressed as the result of an alien invasion, in The Prince of Darkness the homeless are presented as all being minions of evil. The film got a bit of publicity out of the fact that Alice Cooper is featured as one of the evil street schizos, but he never really does anything other than stare gap-mouthed at the church or impale one or two faceless victims.
Whereas Five Million Years to Earth features an ancient spaceship that releases evil unto the world once discovered, The Prince of Darkness has an old canister of green ooze that slowly releases evil unto the world. In Demons and Demons II (1986 / trailer) there were infectious body fluids that changed the people into evil critters (an idea that became a staple to horror films as of The Night of the Living Dead [1968 / trailer] at the latest), in The Prince of Darkness there is either infectious, spurting ooze or projectile puking. The canister, from which the evil first oozes, hidden from the public in a church in downtown Los Angeles for thousands of years (!) by The Brotherhood of Sleep, a once super-powerful secret society within the church (so secret that it is even unknown to the Pope), is discovered by Father Loomis (Donald Pleasence) when the last of the Brotherhood dies. Loomis calls in quantum physics professor Edward Birack (Victor Wong of Big Trouble in Little China [1986 / trailer] and Tremors [1990/ trailer]) to study the thing, who in turn drags in some dozen students and other people for the weekend. Of course, in no short time the ooze decides to ooze out and one by one the bodycount grows as the various idiots wander around alone and get puked on.
Kelly (Susan Blanchard) is the chosen one who gets to swallow the whole canister and thus become the blood and pustule encrusted entity needed to release the all-powerful evil one from his imprisonment. Brian Marsh (Jameson Parker of White Dog [1982 / trailer]) is the film's nominal hero, but he does relatively little other than make the viewer wish that he would die. Catherine (Lisa Blount of Blind Fury [1989/ trailer] and Dead & Buried [1981/ trailer]) is Brian's nominal love interest who ends up sacrificing herself so as to save the world. But wait! Was her sacrifice in vain? Another typically open ending is tagged on as a last scene so as to let the viewer decide for themselves...
If your New Age mom is into quantum physics then The Prince of Darkness is the film for her, though it probably presents the subject in a light she never really thought about. Other people might like the tastelessness of watching infectious projectile puke flying into the open mouths of various would-be zombies of evil, or the sight of one particularly unimportant and instantly expendable character (Robert Grasmere as "I have two lines in the whole movie" Wyndham) get eaten by beetles. Once Kelly gets her stomach full of ooze, her gradual development into an unstoppable evil is rather scary (primarily because we are forced to watch it along with some character locked in the closet of the room), and how she keeps replacing her head every time Father Loomis chops it off with an ax is also fun to watch. Just try to ignore the thousands of candles lit by nobody, the people walking around alone and stupidly ignoring all the strange things going on, an ignored bruise that is too obviously not a simple bruise to ignore, a girl who stares at an obviously unnatural phenomena instead of running from it, some brainless concept about dreams being a message from the future and the various other flaws in the story.
The Prince of Darkness is definitely no masterpiece, but for a low-budget film it delivers its cheap wares more than effectively. It'll scare the shit out of your kid brother, if he can make it through the quantum physics shit without getting bored. It's definitely better than the Italian version of the story that came out the next year, Michele Soavi's La Chiesa (aka The Church or Demons III [1989 / trailer]).