It can’t have escaped your notice that we are alive in late 2018. Commiserations, etc. It’s a point in history where capital is king, where the performance of every single country in the world is ranked by its GDP, and our limited time to be alive – the minuscule allotment of time into which we must squeeze everything, all experience, eating biscuits and paddling in the sea and sleeping in clean sheets – is often measured by how much money we can eke out of it. Hayley McGee’s new solo show, Ex-Boyfriend Yard Sale, takes our financial systems to their logical conclusion: what does that most feted of human experiences, love, leave us with – financially speaking? What does it cost us?

With a lot of debt to clear and a limited stock of possessions to sell, McGee has collaborated with mathematician Melanie Phillips (not that Melanie Phillips, presumably) to work out what these eight items – gifts from former partners, the relics of eight different relationships – might now be worth. If an item has an emotional resonance, can its value go up rather than down over time? Does having suffered in that relationship make its worth increase? Or decrease?

Over the course of the show, economics jostles with deeply personal storytelling, both sitting alongside real interviews with McGee’s ex-partners – it’s a funny mix, but it more than hangs together. And this is maths not just as set dressing, but at the core of what a show is and why it exists. Having asked Phillips to create a sum that can meaningfully assess the value of her objects, McGee is using numbers to expose our value systems, to consider the whole question of worth, breathing new life into conversations around love that have been taking place for decades – like, what does it mean to say that a relationship ‘failed’? Did it fail just because it ended? What do we leave with that we didn’t have before? If value = being changed by our experiences, is a bad experience ‘worth’ more than a good one?

If it all sounds deeply sell-able, as theatre – the kind of work that can be pithily summarised for marketing copy – don’t worry, because this is a show that is continually turning in on itself, continually deepening, interrogating every assumption you might have brought in with you. Every time you think McGee’s gone as far as the show will go, the whole thing turns again, and becomes something cleverer, funnier, more enjoyable; there’s a real delight in watching a writer-performer as deeply talented as McGee examine her idea from every angle and take you with her all the way.

Over the course of its 90 minute run-time, Ex Boyfriend Yard Sale expands out to consider the cost not only of love, but of making art – the gains and expenditure and possible future gains of the show itself, and to ask the same questions about what it is for, what that need is, that the show does about the experiences of romantic love. This is self-reflexive, occasionally quite meta-textual theatre, but it never feels self-satisfied because it’s always driving forward, working to make every five minutes deeper, more considered than the last – and more satisfying for its audience.

Still, 90 mins is a long-ish run time for a solo show and there are points where the pacing doesn’t feel totally held by director Mitchell Cushman, with some moments feeling a little baggy. Even this is folded into the work itself, as McGee discusses the long time she has spent developing the show and her struggle to complete it. Anyway, any less successful moments are infinitely forgivable because of the complete sincerity and commitment of writer-performer McGee, as well as her taut, absolute control over her audience.

There are points at which the material is obviously, at least in some ways, painful – but McGee never lingers long over these moments, always moving onto another thought, another joke. It’s an almost musical sense of the mood in the room. In one section, McGee reads an anonymised email from one of her more recent exes (all identifying features removed) in which he comments on the show and his desire not to be discussed in it. He dismisses the whole idea of the show, damning personally-driven art by young women, before going on to mention his own forthcoming book of memoir. This double-think – that a man’s personal art is Truly Art, a woman’s indefensible attention-seeking – gets a huge laugh from the audience. But he also calls McGee a brilliant performer of ‘other people’s words’. It’s such a brutal thing to say to somebody, especially somebody you’ve known as intimately as an ex-partner, that you feel the force of it – that it must have hurt, even though she’s taken ownership of it by reading it out every night.

These moments bring a huge emotional depth to Ex Boyfriend Yard Sale. Romantic relationships are often the ones most clearly define our relationship to ourselves across our lifetimes, and how we feel we deserve to be treated. To ask what they are worth is to consider the worth and value of our own lives, in every sense. This is intelligent theatre – deeply felt, consistently hilarious and hypnotically honest – that’s been carefully made.

Ex-Boyfriend Yard Sale is on at Camden People’s Theatre until 8th December. More info here.