In horror, as in most film genres, simplicity is power, and the lean initial premise here is as potent as it gets. One morning, a motionless, black-shrouded woman (Okwui Okpokwasili) appears on a chair in the garden of the isolated farm of widowed Ramona (Danielle Deadwyler) and her two children, Tay (Peyton Jackson) and Annie (Estella Kahiha). And while the mysterious figure remains seated and still, she seems to be getting closer.

The inexorable, creeping chill of this uncanny game of What’s the time, Mr Wolf? dissipates almost entirely, though, during a convoluted third act in which the story ties itself in knots and the audience becomes too baffled to remember to be scared.

• In UK and Irish cinemas