Screens at CIFF: 10/12 & 10/13 & 10/15
World premiere: 11 March, 2012, South by Southwest Film Festival

No film that opens with as big a moment as Citadel does can possibly be written off entirely: a young husband, living with his wife in a virtually uninhabitable public housing building too-ironically named "Edenstown", has just stepped into the elevator when he sees a cluster of hooded kids jump on her in the hallway, beating her savagely, as the ancient piece of equipment refuses to obey his frantic button-pressing. By the time he gets back, she's unconscious, with a needle driven right into her pregnant abdomen.

That's a real kick in the head, any way you want it - swift, brutal, visceral (the shot of that piece of junk jabbed into her bleeding body is precisely that sort of sickening shock of violation that horror, at its best, is all about ), upsetting. Lots of movies wouldn't live up that beginning, so we should not look down on Citadel for the fact that it opens with its best scene.

But the fact that so very few of the scenes to follow in the subsequent 80 minutes are even vaguely interested in that level of intensity; that we can happily look down on the movie for. And since horror films that have one truly great moment followed by a whole mess of not living up that moment are, in their way, among the most frustrating of their genre, we can look down it with particularly arch smugness.

Returning to the story eight months later, we find this young husband, Tommy (Aneurin Barnard), suffers from severe agoraphobia as a result of the attack, severe enough that there's a real question as to whether he should be left the guardian of the baby who was successfully removed from his wife's bleeding body before she was consigned to the coma that has kept her ever since, a come from which she is now to be released as Tommy allows the doctors to take her off of life-support, leaving him truly alone.

Two people are on hand to help him: one is social worker Marie (Wunmi Mosaku), who is really anxious that he should be brought back to enough mental health that he can be a good father; the other is the local crazy priest (James Cosmo), who doesn't "help", so much as bellow at Tommy that "they're" coming for his little daughter. And "they", claims the priest, are the kids living in the abandoned Edenstown buildings, not even proper humans but some kind of mutated monsters that can smell fear and, for private reasons, want to kidnap normal children. Marie dismisses this as so much paranoia about the desperately poor; but Tommy is erratic enough that the priest's claims that they should team up to burn the strange youths' building to the ground doesn't seem entirely unreasonable.

Does that sound like a psychological thriller about a man who's so emotionally broken that he can't parse reality from fantasy, trying to figure out whether he should believe the sensible bureaucrat or the ranting priest and the limited evidence of his own eyes, to you? Because it sounds like that to me. And it's absolutely not that - there comes a point where we get rather graphic and unmistakable evidence that Marie is completely wrong and the priest is completely right, and all that leaves is for Tommy, the priest, and the priest's ward Danny (Jake Wilson) - a blind pre-teen who can somehow block the mutants' ability to detect fear - to go hunting for Tommy's kidnapped daughter, and kill the whole lot of beasts. Which is a disappointing way for the plot to head on two different levels: first, it's simply not as interesting - who'd rather see a coward learn to stand up the monsters when the possibility of watching that same coward grapple with his only mental unreliability is right there - and second, it turns the first half of the movie, which seemed like such an atmospheric slow-burn at the time, into a complete waste, given how much energy it spent in setting up situations that don't pay off and the amount of dialogue dedicated to a message about life in the slums that just sound ridiculous once we learn that, in fact, these poor people really are just as dangerous and awful as they seem.

Besides which, theme and plot notwithstanding, Tommy is a poor excuse for a protagonist: with his arc consisting, in its entirety, of "agoraphobic man learns to be brave", and that only coming about through the application of an old-fashioned Magic Feather, he's neither deep enough nor dynamic enough nor - critically - real enough to capture our attention as the anchor for a character-based horror film; and with its relative lack of scare scenes, Citadel is clearly aiming for psychological thrills more than visceral ones.

Now, fair is fair, and the last third of the movie is pretty fine horror, if much shallower than writer-director Ciáran Foy apparently wants it to be. The under-lit interior of the abandoned apartment is exactly as spooky as it needs to be, and the makeup on the mutant kids, barely glimpsed in the murky light, is genuinely unsettling; throw in a nice crawling pace and echoing sound design, and there's a solid 20 minutes of pretty terrific horror atmosphere. Is that enough to justify the wandering, pointless, frequently dull hour that precedes that point? Not by my reckoning, though at least Citadel is an example of talent going to waste rather than incompetence wrecking a movie that was already bad, and one can't ask for too much when it comes to indie horror, after all. Plenty of them wouldn't have ever gotten to that 20 minutes, nor that opening scene, in the first place, and for that, if nothing else, Citadel isn't a complete waste of time.