A trio of Jehovah's Witnesses in different kinds of crisis are at the centre of the first feature from writer-director Daniel Kokotajlo, who was brought up in the faith. Siobhan Finneran (TV's Happy Valley) is Ivanna, a single mother in Oldham raising two young women, Luisa (Sacha Parkinson) and Alex (Molly Wright), in strict accordance with her beliefs. While Alex is pious and obedient even as she turns 18, her more worldly sister, who attends college and socialises more widely, harbours doubts which an unplanned pregnancy bring cascading to the fore.

Apostasy is critical of the faith, its peculiar punishments and what could be perceived as a lack of compassion in desperate circumstances. Static camerawork reflects the religion's rigidity and the sombre palette and use of silence shows how living under the shadow of a pending apocalypse can suck the joy out of existence, especially for the young. Meanwhile, the dangerously anaemic Alex is under great pressure to turn down a lifesaving blood transfusion should she require it; children who have done so and died are glorified by the church.

However the film is deeply sympathetic toward believers. It might sometimes hold the audience at a dispassionate remove, with its dimly lit views through doorways, but it balances this by bringing us in close when it matters and engaging impressively with the difficulty of reconciling the requirements of family and faith. Ivanna's love for her daughters is never in doubt – that it brings her into conflict with something she believes in so fervently can be heartbreaking to watch. Finneran is typically magnificent as a humble disciple undergoing a very private struggle, with Parkinson and Wright providing accomplished support.

Demonstrating a steady hand in the face of incendiary and personally challenging subject matter, Kokotajlo's debut is a meticulously measured drama that shows the toll of prioritising religious adherence over all else.

Selected release from Fri 27 Jul.