“You’ll go days without sleep, fasting, back-breaking rites, ritual sex – you’ll be at the very edge. You ready for that, darlin’?”

Trust me – you’re not.

Liam Gavin’s utterly original and psychologically disquieting horror may only be 100 minutes, but it covers months of an intricate occult ritual designed to allow bereaved mother Sophia (Catherine Walker) to speak with her guardian angel, and in turn, her dead son. Her unlikely guide is Joseph Solomon (Steve Oram), a brusque, tracksuit-wearing Londoner who looks more suited to working in a bookies than communicating with angels.

As Solomon convinces Sophia to buy eight months’ worth of food and forbids her from leaving the dilapidated Welsh house she bought for the ritual, the question lingers: Is Solomon actually able to harness the occult, or is he a conman taking advantage of a grieving woman? Gavin allows these questions to unfold slowly, as we realise that either answer is utterly terrifying. Oram is a powerhouse, deploying his volcanic energy in a more ominous way than his darkly comic turns in Sightseers and Aaaaaaaah! His explosive crudeness is a perfect contrast to Walker’s quiet, ghost-like energy; a woman shattered by grief and held together by one goal: to see her son again.

Rituals involving blood drinking, candlelight, sexual bullying and possible gaslighting force Solomon and Sophia into a battle for power. A Dark Song becomes an intensely intimate chamber piece; a character study under the most extreme circumstances.