Emilija Trajkovic as Lucy, Archie MacGregor as Bart, Rob Das as Adrian, Milan Verma as Nigel, Nekisha Eric as Joy in Beginners
Emilija Trajkovic as Lucy, Archie MacGregor as Bart, Rob Das as Adrian, Milan Verma as Nigel, Nekisha Eric as Joy in Beginners
© Hugo Glendinning

No seven year-old feels like a seven year-old. Seven, to them, seems impossibly old; the oldest they've ever been, in fact. They're more mature than ever, more worldly, more capable; not minors, but people in their own right.

Conversely, no adult ever feels fully adult – not properly, not yet. If we do, adulthood seems impossible too; perhaps more impossible than ever. No matter our age, we still feel like children; unworldly and incapable; big kids at heart.

The brilliance of Tim Crouch's Beginners is that it realises both things at once. By having adults play kids – without ever acting as such – it takes children seriously and shows the world as they see it. Purni Morell's Unicorn has always sought to do that and the final show of her tenure is right up with its best.

Four beds sit haphazardly on an expanse of yellow carpet, as if marooned on a desert island. Each is occupied by an adult, all talking oddly like children in stilted, strangely inarticulate sentences. One's pushing a pram, another's carrying a gun. Occasionally, they're joined or replaced by child doppelgängers. A fifth bounds around unblinkingly, this way and that. Nothing quite makes sense.

It takes a while to work out exactly what we're watching: namely, four kids bunked up on a wet Cornish holiday, left to their own devices by parents drinking downstairs. They're cooped up together, not out of choice, with only the dog, Sandy, for company. Wouldbe ballerina Lucy (Pandora Colin) plays mum, while pompous Nigel (Neil D'Souza) holds court. Jacqui Dubois's Joy keeps herself to herself, while Rob Das' new arrival, a Dutch boy named Bart, does his best to fit in and reach out to new friends.

Taking us into their world – a privileged peek into a child-only space – Crouch shows us these children as they see themselves. Their games take on a level of reality: real guns instead of toy pistols; proper prams for their dolls. So do their concerns, be it boredom, abandonment or their fears for the future. Lucy's troubled by the fact bees are dying. Nigel's unsettled by his dad's new relationship. To adult eyes, it's all painfully familiar: the tears beneath duvets, the fights between friends. It takes you right back. Who knows what kids see: maybe adults being silly, maybe their experiences given space.

Either way, it's a gorgeously generous gesture. Crouch gives these four children – not to mention Amalia Vitale's delightfully deadpan dog – the means to express themselves fully. Their end-of-week show takes on an expansive theatricality as Chloe Lamford and Camilla Clarke's design comes into bloom: as big and beautiful as any Royal Ballet stage. Instead of fumbled silliness and make-do outfits, we see a full-bodied drama: a tale of absent adults and child heroes pitted against death. Imagine Anne Washburn's Mr Burns but for kids – and big kids alike. Bliss.

Beginners runs at the Unicorn Theatre until 15 April.