Set and shot in Wales, with dialogue in Welsh (apart from a few loan words from English and the occasional Anglo-Saxon cuss), this is a striking, reasonably original wodge of folk horror. It also represents an auspicious first feature for director Lee Haven Jones (he’s shot a few Doctor Who episodes and the like), working from a script by writer-producer Roger Williams. Said screenplay adroitly incorporates meaty subtexts about class and generational tension, the evils of contemporary land management, and sexual abuse, while still ensuring there’s plenty of screen time devoted to cannibalism, torture and very gory forms of sex.

The feast of the title is a dinner party that arrogant local MP Gwyn (Julian Lewis Jones) and his preening, social-climbing wife Glenda (Nia Roberts) are throwing for a developer friend (Rhodri Meilir) and a neighbour (Lisa Palfrey), a spread that will feature rabbits killed by Gwyn. The couple’s ne’er-do-well sons – recovering addict Guto (Steffan Cennydd) and creepy triathlete Gweirydd (Sion Alun Davies) – are also on hand. To help prepare and serve, the hosts have hired a local girl, Cadi (Annes Elwy) to help when their usual caterer can’t make it, but Cadi turns out to be a skittish, otherworldly creature who reacts oddly to the sound of gunshots and seems to have an agenda of her own.

Viewers tuned into this sort of genre will suspect something supernatural is up pretty quickly, around the time people start coughing up weird tangles of material and then continuing about their business like nothing happened, like cats bringing up hairballs and then resuming grooming serenely. Jones skilfully cranks up the creepiness a notch at a time with an ominous soundtrack and stylish lighting, until the dial is way past 11 and into grand guignol territory by the end.

• The Feast is released on 19 August in cinemas.