Ella Road’s stunningly assured debut play is about blood. It is already becoming increasingly easy to use the red stuff to predict disease, but Road takes this development further, imaging a world in which companies decide whether or not to employ someone based on what latent diseases their sample reveals.

It is the job of Bea (Jade Anouka) to feed the samples into a machine that spews out a score of between one and ten. Anyone with less than eight can forget a job in the City or law.

Meanwhile, personal relationships are based on the number too as it is hard to imagine that someone in the top 20 percent is going to want to have children with someone in the bottom half, even if the low scorer has a higher IQ.

For instance, Bea (a 7.1) has fallen for Aaron (Rory Fleck Byrne) who not only has an 8.9 but is also a descendant of Lord Alfred Tennyson, Bea’s favourite poet, which can only add to his charms.

But as good as they are are together — and Anouka and Byrne have a kind of beautiful people aura about them — they are determined to escape the prejudices that have emerged in a society driven by a ratings culture.

In fact, “ratism” has taken the place of “racism”. People with a known high score are being murdered and then bled so that their blood can be used to provide fake samples.

If that seems a tad far fetched, Road meticulously constructs a logic that allows her dystopic vision to become convincing.

And this is helped by Sam Yates’s taut production which conjures a Britain that feels very much like now.

Environmental concerns are subtly woven into the narrative. Fresh fruit is a delicacy; charities advertise to combat the growing problem of malnutrition in British children; beriberi is on the rise. Yet none of this is sensationalist.

Rather, the issues that inform everyday life here are very familiar. This is merely the logic of what happens next.

The performances are strong but it is the sure-footedness of Road’s plot that really impresses, right up to the well-disguised twist that elicits a gasp of astonishment from the audience.

You leave satisfyingly unsettled, yet buoyed by the fact that however accurate Road’s vision of the future turns out to be, it will at least include a new dramatic voice.