Scary movies aren’t just for Halloween. This smart, emotional and very frightening film has a universal resonance, being mainly about dementia and caring for our ageing parents.

Emily Mortimer stars as a Melbourne woman returning to her mother’s house in more remote parts, following a phone call that her Mum’s gone missing. She travels with her own daughter, played by Bella Heathcote, naturally anxious about her Gran.

The elderly woman (“She’s in her 80s, you know, she forgets things,” is how Emily tells it to the police) eventually turns up, bedraggled and muddied, having clearly been wandering in the woods but not prepared to tell.

Gran is played by renowned Australian stage actress Robyn Nevin and she’s excellent here, mixing affectionate glances with piercing anger, affecting mild irritation with distressing confusion. Or could it be some kind of possession? Is dementia the ghost, stealing away the spirit of someone we no longer recognise? What an awful but brilliant premise for horror.

Noises clunk in the house, and there are Post It notes left all over the place, from innocent reminders such as Turn Off Tap to Brush Teeth, to more perturbing scrawls such as Don’t Follow It.

While Emily goes off to look at care homes in the city and sobs quietly in her car at what’s become of her own Mum, Gran turns on her granddaughter and the house gets nasty.

A very simple film, like the best horrors, this plays on our notions of family, ghosts, memory (particularly memory loss) and big, mouldy old houses stuffed with memories and boxes. Even while the tension and scary bits ratchet up in the final stages, Natalie Erika James’ debut film retains a heart, building to some surprisingly emotional moments just where the jumpiest scares might be, peeling away layers of feeling, scratching at guilt and years of resentment as well as deep wells of love.

An impressively disturbing watch.