A woman is brutally murdered while renovating an isolated country house. One year later, the woman’s blind sister (Carolyn Bracken) arrives, surprising her widow (Gwilym Lee) and his new girlfriend (Caroline Menton), and intent upon bringing her killer to justice.

There is a lot of atmosphere to Oddity, a new horror feature written and directed by Ireland’s Damian McCarthy. It uses its isolated rural setting well, as it does the somewhat creepy aesthetic of the house itself. It also centres on a strong performance by Carolyn Bracken, pulling double duty as both blind psychic Darcy Odello and her late sister Dani. When the film is good it can be exceptional, showing off strong technique and inventive ideas. For the most part, however, it is hobbled by more than its fair share of creative problems – not to mention a key ethical one.

To get the elephant out of the room: McCarthy casts sighted actor Carolyn Bracken as a blind character, denying a performer with disability from a role in favour of an able-bodied one. There really is no excuse for it here, and any attempts to justify the casting – that Darcy and Dani are twins, and need the same actor, and Dani is sighted – simply show off the weaknesses of McCarthy’s script. Why do the women have to be twins? Why not simply sisters? Why does Darcy need to be blind? It is, after all, something of a tedious cliché to employ a psychic blind woman in the narrative at all.

The film also struggles when presenting the mystery of Dani’s murder. Assuming that the alleged killer did not do it (an underused Tadhg Murphy), there are precious few alternatives from which to choose – and that turns a twisting thriller into a long wait for the story to catch up with its audience. Lee is decent as grieving psychologist Ted Temmis. Steve Wall’s melodramatic performance as hospital orderly Ivan fails to match the rest of the cast. Caroline Menton stands out as Ted’s new girlfriend Yana. She is initially positioned as an antagonist to Darcy, and an unsympathetic one at that, but as the film develops she emerges as the most identifiable and realistic character of the lot.

McCarthy introduces a number of potent ideas into his film, notably the inclusion of a massive golem-like doll in Darcy’s possession – which you know from the first frame is going to come to life at some point – and Darcy’s antique shop – which comes filled with all manner of haunted and cursed objects. The promise of the latter is enormous, yet it is as if McCarthy fails to work out how to utilise their potential.

The film also presents a decidedly backwards and old-fashioned idea of mental health. The hospital where Ted works is more Hammer horror than hospital, filled with dark, grimy corridors and bleak, cell-like rooms. Were the film set 60 or 70 years earlier – or indeed made then – it would be easier to forgive. This is 2024, and the bizarrely gothic treatment only serves to destroy any sense of realism.

This is a low-budget independent production, and as such I am always willing to give it a fair amount of latitude in terms of quality. As always seems to be the case, however, the problems are all in the screenplay. McCarthy has identified potent story material, and he demonstrates a strong talent for horror cinema, but he has failed to pull the best opportunities out of his own ingredients. It is a somewhat decent horror film that could have been a great one.