Lungs, 2014’s big success from Paines Plough, is constantly concerned with time. In an hour, a couple’s lifespan has passed. Moments pass by in minutes, seemingly frozen in time, whilst entire years take place over a second of silence. Sian Reese-Williams and Abdul Salis play the couple in question, whose story begins as they debate the environmental impact of raising a family. They don’t live in an eco-dome and produce their own crops; this is a genuine, inconspicuous duo with real concerns about the Earth. Duncan Macmillan’s dialogue, complete with ums and errs, brilliantly shows a couple grappling with issues outside their control.

The play has the effect of taking place across one scene: a whole life playing out without a change in physicality. To indicate a change of scene is the slightest of pauses, with the actors’ tone the only real indication that time has passed at all. Very rarely are we given a substantial lighting change; this is text and performance in its most restrained form. Lungs requires investment in the characters from its audience, with a piece that strips the theatre down to two actors whose physical distance suggests the relationship’s progress.

Time creeps up on the couple quickly, as they’re wrapped up in discussion. There isn’t a great deal of action; they oscillate around each other and the matter at hand in the roundabout space, coming to a conclusion without hastening to act. Reese-Williams, scraping her fingers through her hair, boils over with frustration and a need to let out her emotions whilst Salis bottles up. These characteristics are reversed in a devastating scene at the play’s centre.

Lungs is a delicate and really beautiful play, as deeply humorous as it is touching. Everything about the play is superb, as it ebbs and flows through a couple’s timeline. All too soon, years of inaction catch up in a poignant and entirely appropriate finish.

Lungs is playing at Roundabout @ Summerhall until 30 August (no performances on 20 or 22) as part of the Edinburgh Festival Fringe. For more information, visit the Edinburgh Fringe website.