Dead. The word echoes unspoken through much of the 75 minutes of Jack Thorne’s two-hander about a couple coming to terms with hideous tragedy. And yet at first the piece seems worlds away, as husband and wife alternate an account of comprehensively bad sex. Genevieve Barr and Arthur Hughes stand upstage on a vertical-bed arrangement, each describing how the other does various physical things wrong but they themselves try not to let on.

The physical is a defining element in virtually any production by Graeae Theatre Company, who work with and for deaf and disabled actors… and yet at the same time it isn’t. This isn’t a story about living with any condition (although the character Alice, like Barr, is deaf), but about trying to sustain a relationship through a traumatic event. The bad sex guide is interrupted by accounts of how Alice and Phil met, their first dates and so on: “To this day I still have no idea what he signed,” says Alice of the moment when Phil tried to show off his efforts to learn sign language.

Thorne (scriptwriter of the keenly anticipated stage diptych Harry Potter And The Cursed Child) is particularly good at writing about bare emotions under extreme stress, whether that stress is bizarre (he also wrote the stage version of child-vampire tale Let The Right One In) or all too ordinary, as with Alice’s ante-partum haemorrhage. The horror of “dead” hangs in the air for so long, but when finally uttered it is immediately topped by the horror that Alice must nevertheless go through labour to bear her already-dead child. By now the writing is consistently heartbreaking, through the climactic event and its aftermath and back to the bed for what is now revealed as a desperate yet determined act of reaffirmation.

Amit Sharma directs simply and honestly, bringing the actors down from the bed/podium to narrate past episodes to us and to speak to us directly. The National Theatre’s Temporary space (formerly the Shed) has welcomed a number of top-quality visiting productions, but with Sugar Water (first seen last summer in Plymouth and Edinburgh) it goes out on a high note.

Written for the Financial Times.