Paul Duane is the film-maker who in 2011 made Barbaric Genius, a gripping documentary portrait of ex-convict, ex-vagrant and tournament chess player John Healy, whose memoir The Grass Arena is a classic of outsider art literature. Now Duane has given us this horror film which, though it begins with interesting subversive and satirical ideas, and an interesting allusion to Guillermo del Toro, finally becomes, for me, simply too chaotic, strained and unfocused.

Anna (Simone Collins) and Aleks (Charlie Maher) are social historians who travel around remote rural pubs in Ireland, recording folk ballads; they become fascinated by rumours of an old woman who lives thereabouts who can sing a thousand-year-old song, taught over generations from mother to daughter, which has never been recorded or transcribed on paper. Asking questions about her makes locals suspicious; Anna and Aleks assure one man that they are not journalists or interested in anything “political”, but he replies darkly: “There’s nothing that’s not political …”

He’s right. The act of recording an Indigenous or vernacular culture for outsider consumption – and thereby encouraging outsider interest and intervention – has social and political implications. But for them, the implications go further. The song is taboo, setting it down is a transgression, and uncovering this tortured folk ballad of ageless pain and rage has summoned up forces of evil. It is a good idea and there are good moments in the film, especially at the very beginning when Anna and Aleks have a bizarre encounter with the old woman herself, Rita Concannon, strikingly played by Olwen Fouéré. But then things begin to slide. There are however some resonant ideas here.

• All You Need Is Death is in UK and Irish cinemas from 19 April.