There are three parts to Thomas Eccleshare’s two-hander Heather. The first is an email exchange, read aloud by Ashley Gerlach and Charlotte Melia – both seamlessly excellent – into microphones. She’s a writer, Heather; he’s her publisher, Harry. She’s created a best-selling fantasy series. He’s helped her do it. They’ve never met.

The second part is a clipped conversation between Heather and Harry, in person. And the third part thrillingly delves into the magical world Heather has created: Gerlach and Melia jump around the sparse stage, feverishly evoking an ethereal world of death and danger to Iain Armstrong’s cinematic sound design.

If that sounds an elliptical description, it’s because there’s a lot to give away. Eccleshare twists his story on its head multiple times, pulling the rug out from underneath the audience with downbeat dexterity. What begins as a charming, lightly satirical correspondence between author and editor suddenly becomes something far darker – and far more compelling.

Questions about prejudice, preconceptions and the honesty and integrity of art rear their heads. Although they’re not entirely explored in Eccleshare’s whirlwind final third, the velocity at which they arrive lends them a hair-raising immediacy. This is ferociously smart writing, slickly staged.