Diabolic review – Mormon-country horror takes ayahuasca down to the creepy cellar

Underground doors and regression therapy – it sounds like a can’t miss for the genre, but the knockout blow is never delivered Though it features few recognisable faces, this Australian-shot, US-set indie horror displays a core competency that gets it some of the way to where it’s heading – only to collapse in the final reels into the usual hacky manoeuvres. Ten years after fleeing a fundamentalist branch of the Latter-day Saints, snub-nosed artist heroine Elise (Elizabeth Cullen) has started shunning the attentions of boyfriend Adam (John Kim), instead obsessively digging holes in the couple’s back garden and trashing the living room in the middle of the night. Could it have something to do with the grimy cellar door she feels compelled to paint, or the traumatic baptism we witness in a pre-title sequence? What are the chances? For somewhere between half and two-thirds of its running time, we’re watching a diagnostic case study: Elise and close pals return to Mormon country – more specifically, the in-no-way ironically named hamlet of Haventon – to undergo a regression therapy involving an ayahuasca variant; this will strike anyone as ill-advised even before an act