The Solid Life of Sugar Water (Temporary Theatre, National Theatre)

There aren't many places more intimate than a married couple's bed. And that is exactly where Jack Thorne sets his remarkable and intense play The Solid Life of Sugar Water, which arrives at the National following a tour. It's less a ménage à trois, more a ménage à the entire audience.

Thorne, who wrote the play for Deaf and disabled-led company Graeae, thrusts us into this excruciatingly personal space and focuses on Alice and Phil who are trying, and mostly failing, to have sex. At times, listening to the graphic explanations of their fumbles is acutely and hilariously awkward. There's mention of his 'magic' technique, 'finger dildos' and her bored impatience at his insistence on foreplay. It's very, very funny, until we begin to understand the reason why they are struggling.

Alice and Phil are trying to put themselves and their relationship back together after the loss of a baby. Explicit, witty and heart-breaking, the play centres on a moment in their lives that is so vulnerable, so delicate, so in danger of breaking apart, that you hold your breath for fear of intruding on their journey. It's a beautiful, poignant piece of writing that is sensitively observed: "I'm pretty ripped up. Tender." Alice says, matter of factly, and it is so clear she is – both physically and emotionally.

Amit Sharma's production has a superb set from Lily Arnold which is the entire floor of a bedroom turned vertical. We see the couple, and the room, as if we were hovering above them. It makes us feel as though we are voyeurs, looking in on moments that only a husband and wife should witness. The entire piece is accompanied by surtitles which pop up all over the walls of the set. The Solid Life of Sugar Water is about communication; the characters talk out to the audience and we can clearly read everything they say, but subtext hangs heavy and by the end you are willing them simply to talk, not to us, but to each other.

Deaf actor Genevieve Barr plays the woman and she is excellent – she feels like a remote island from her husband, the chippy, eminently watchable Arthur Hughes. Both Barr and Hughes bring a sturdy realness to their roles, which makes watching The Solid Life of Sugar Water far from depressing.

This is a brilliant piece, a convincing snapshot of a modern tragedy depicting an elegant and complex intertwining of sex, death and love.

The Solid Life of Sugar Water runs at the Temporary Theatre, National Theatre until 19 March.