The military have captured some kind of supernatural force and imprisoned it in a deep underground bunker with terrible lighting, and electronic doors that seem to employ the voice of Pod from 'Snog, Marry, Avoid'. Civilian Hayley is an expert who talks to ghosts and wears space invader patterned trousers. She has been brought in to try and communicate with "the entity", despite the scepticism of some of the military types down there ("You may as well be an aromatherapist"). It's bad enough while the force is imprisoned within its special cage. But what happens if it escapes..?
The first half of the film uses the darkness, background sound, the ever-present CCTV cameras, and the sense of being cut off from the outside world, to successfully build a claustrophobic tension. Almost all the action takes place underground and in near darkness, with just a few dramatic spots of light, lots of industrial pipes and mesh, and occasional clouds of smoke or steam. It reminded me more of an 80s nightclub than a convincing military base, but if you can overlook the unlikeliness of it being so badly lit down there, it does create a creepy atmosphere.
The "entity" itself is not actually seen - which works in the film's favour. It manifests itself by 'possessing' and controlling certain characters (it has a particular fondness for making them sing Frere Jacques). CGI is kept to a minimum, other than the red static-like effect in the holding cage, which reminded me a lot of the monster from the Id in Forbidden Planet (1956).
The film changes direction at the half way point, when the "entity" escapes and passes from one person to another, giving it a similar theme to The Thing (1982), The Hidden (1987) and Jason Goes To Hell (1993). The action becomes a kind of horror version of 'tag'. Characters are not sure who to trust, but I didn't feel this element was used to its full potential.
I liked the atmosphere in Stormhouse, and I thought there were some good moments of suspense and tension. The acting was mostly ok but nothing to get excited about, apart from the authority character who arrives part way through, whose poor acting was very distracting indeed. The script is another weakness, with clunky dialogue at times. And there is a sequence near the end involving a basketball, which is bafflingly pointless.
Overall I thought the film was entertaining if you try not to think too hard about it, with a few scary moments, but you'll probably forget all about it within a few days. 3/5