Reportedly inspired by a violent mugging experienced by writer/director Ciarán Foy, this hopelessly muddled horror movie takes place in a United Kingdom public-housing high-rise so dingy and bleak you might feel that razing it would be a mercy. Tommy Cowley (Aneurin Barnard) and his very pregnant wife, Joanne (Amy Shiels), were planning to escape it, but as Citadel opens, Joanne is attacked in the hallway by a band of hooded, shrieking children who stab a dirty syringe into her belly. Her newborn survives, but Joanne dies, leaving Tommy with an infant he can’t handle and a severe case of agoraphobia. Thanks to Barnard’s exquisitely stressed-out performance, Foy builds a palpable sense of unease, but when it comes time to explain what was in that syringe, as well as the intentions of the little monsters who wielded it, the filmmaker fumbles. Tommy turns to an embittered priest (James Cosmo) for guidance, and the explanations become a blur of words that boil down to the least satisfying of answers. Here’s a spoiler, if you care: If it’s all in his head, Tommy would do well to conjure himself a nicer apartment.