Cardstock is an exchange of thoughts – a dialogue of a kind – between two women who never meet, but leave a crucial imprint on each other’s lives. On one side of the stage, we have internet author Mae; on the other side is Lily, an avid online reader and Mae’s most ardent fan. The title refers to extra-thick paper, which – if you crease it the right way – can hold a shape and stand up on its own. It takes strength to stand up… and courage to speak out, too.

Mae writes BL (“boy’s love”) fiction, a genre of erotica primarily read by women, but where the sexual encounters are between gay men. If that seems odd, then Lily explains that these ideal men feel safe to her: they don’t sweat, don’t smell, and they won’t sit too close to her on the sofa. Her mum doesn’t know “what happened”, she ominously remarks. Actor Xinyue Zhao powerfully portrays a once-vibrant young woman, whose only remaining defence is withdrawal into herself; but she’s sweetly excited when Mae’s next chapter drops, and she can escape again into an imagined better world.

We do get to see a scene from one of Mae’s stories, and it’s stilted, hackneyed – an artificial image of perfection. Mae isn’t ashamed of the bald commercial logic of these synthetic stories, and it’s her growing success that triggers the quandary at the heart of the plot. But there’s plenty of humour along the road to that crisis: in one particularly entertaining segment, lines from the two women are cleverly interleaved, to contrast the red-carpet world that Lily is picturing with the humdrum reality of Mae’s offline life.

Writer Qianyue Ang grew up in China, and censorship is an important second theme in play. Mae is unwittingly playing a dangerous game: though she publishes her stories on a website outside China, the penalty for attracting attention to Lily’s cause could be severe. The topic’s clearly important to Ang, and the two big stories do dovetail well, but I worry that the shadow of the state gives British audiences too easy a way out. Troublingly, if we look past that detail, the dysfunctions of society we witness in the story could all develop just as cruelly here.

For all the darkness of its subject matter, Cardstock is an elegant and starkly beautiful play. The beauty comes through in the crisp monochrome set, or In Lily’s poignant memory of a perfect bowl of soup. But the final image of Ching Chen (Jin), playing Mae, is a haunting one: sad, tired, resigned yet defiant, facing a future shaped by the choices she has made.