We’re greeted first by a youngish girl, on a creepily darkened stage. On the face of it, her story’s a simple one: born in the early 1900s, the only child of an Irish immigrant couple, the product of a working-class father and a proud but image-conscious mam. But why is she scared to look behind her? And why is the hatch to the attic ajar?

Suddenly, a change of scene – and in brighter light, a quintessential jolly good chap hands out brisk instructions to his apparent junior. They’re writing a novel, it seems, something to do with supernatural forces and ancient lore. It’s very much his storyline, for all that it’s her words telling the tale.

All three characters are played by solo actor Jasmin Gleeson – and their secrets are unwrapped slowly, one measured revelation at a time. It’s unclear for a while how the stories relate, what’s real life and what is fiction. But through subtly-dropped hints and carefully-placed words, we come to understand the connection between the three people; we sense the shape of their personalities, and the nature of the force transcending humanity that hovers behind them all.

The most compelling scenes, for me, are delivered in the voice of the Irish child. We hear about the hardship her family faces, the prejudice and the disappointment, the punishing hours her father works and the gradual toll extracted. The relationship between the two authors is more of a riddle – intentionally and cleverly so – and their portrayals felt a tiny bit less authentic to me. But I still cringed at the male writer’s breezy ascendancy, the unthinking dismissal of his talented partner as a reclusive “indoor cat”.

There’s a message here about artistry, and the power of expressing your own distinctive voice in the face of insipid commercialism. There’s a deeper theme, too, about “strangeness” – the sense of not quite fitting in – and how it can be passed down through generations. In different times, we might look on “strange” families as outcasts, people with tainted blood; but this twentieth-century tale pitches it differently, both in understanding how “strangeness” is passed on and the inner power it can bring.

Josh King’s script has many obvious influences, most notably the professorial figures underpinning many of MR James’ best-loved tales. Shirley Jackson, after whom the play is named, is present in spirit too. But this is first and foremost a thoughtful original work – which hints at occult secrets, but ultimately reveals something more interesting still. It’s gently scary and often saddening, yet there is power to be found in the strange.