The Human Voice is a monodrama, a stolen conversation, a phone call that no one is supposed to hear, perhaps not even the person on the other end of the line. And yet there we are, wearing headphones so we can sneak even more closely into this woman’s life, so we can hear every breath and every sight. We are witnessing her last phone call with her lover, as much as in Jean Cocteau’s La Voix Humaine, which the show is inspired by.

The setting is wonderfully alienating – we observe the woman (Leanne Best) as if she is trapped in a zoo cage. She smokes in the room, climbs on the sofa, looks outside the windows. Everything is credible and imbued with everyday-ness. Everything is just as real as the set design by Sarah Beaton – concrete, cheap, messy.

The experience of watching every action of the protagonist during her phone call has really deep implications. On the one hand, what she’s having is a private conversation, but on the other there’s a voyeuristic impulse to want to see more, to hear more, to learn more. Why did the relationship end? Why is she constantly lying, to herself to begin with? Why is he not hanging up? Why does he keep listening to her confused blabbering? She goes from “I feel brave” to “I’m on autopilot”, and Best is absolutely magisterial at fleshing out this deep confusion.

Early on in the show, the couple struggles to get good signal and the call gets cut off several times. The repeated, frustrating dropping of the signal feels like a metaphor for the times where we “lose connection” with our partners, when even if we’re still technically with them, they sound and feel impossibly far away.

More poignant still is the moment when the protagonist opens up completely and unconditionally to her ex lover. She decides to be vulnerable and fragile. She chooses to lay bare her heart to the very person who tore it apart. In all her suffering, she cannot put an end to the conversation, which turns out to be as indispensable as the air she breathes. Addicted to her lover, she clings desperately to whatever remains of this toxic relationship – namely a virtual, impersonal phone call.

There’s incredibly moving acting and much food for thought. It’s tempting to think what would happen if the man dropped the conversation and decided it was simply too awkward to keep listening to such an unfiltered confession. But in the overall architecture of the monologue, it makes sense to fully embrace fragility and despair, so as to deliver a performance that’s so human that it’s painful to watch.

The Human Voice is playing at the Gate Theatre until 6 October. For further information and tickets, please click here.