For fifty years, the Sherman has made it its mission to be a theatre of Wales and for Wales. In the last few years alone, it has boldly reinvented the work of Ibsen, Chekhov and Shakespeare and carved a space for budding Welsh and Wales-based creatives to shine. Its anniversary year is packed with a triple crown of creative artistry: first there was Ghost Cities, a reworking of Gary Owen’s Ghost City performed and with new material by the Sherman Youth Theatre; coming up in May there is Nia Morais’ Imrie, a Welsh-language odyssey co-produced with Frân Wen; and this month we are treated to Romeo and Julie, which sets its star-cross’d love story in Splott.

Co-produced with the National Theatre, Romeo and Julie is the latest collaboration from writer Gary Owen and director Rachel O’Riordan, the powerhouse creative duo behind Iphigenia in Splott, The Cherry Orchard and Killology. Rosie Sheehy (King John, RSC) is Julie, a budding astrophysicist on the fast-track to Cambridge. Callum Scott Howells (It’s a Sin, Cabaret) plays Romeo, a young single dad struggling to raise both a newborn and an alcoholic mother (Catrin Aaron, flawless). He meets Julie not at a starry party but in the STAR Hub Tremorfa, where sparks fly and fates align. Their chemistry is in the physics and the physical: in Julie’s explanations of quantum theory to a starry-eyed Romeo, and in the brawny balletic interludes that literalise their connection. It’s a muscly, messy love; one that seeps into the cracks.

Sheehy and Howells are magnetic both together and apart. There is a striking synergy between the pair which keeps the audience invested in their doomed love, even as the choices they make turn from the sublime to the ridiculous. Fabulously bolshie and oozing bravado, Sheehy has shades of the original reckless Romeo, while Howells’ performance as the sweet young romantic gives the play its beating heart.

It’s a testament to the skill of the ensemble, and to Owen’s script, that the play is ultimately as comedic as it is tragic. Its distinctly Cardiffian sense of humour finds the light in the darkest of moments. Much of its finest quips can be credited to Catrin Aaron’s aptly-named Barb, who certainly throws around a fair share of gin-soaked jibes. Meanwhile, Paul Brennen and Anita Reynolds complete the thrilling ensemble as Julie’s concerned parents, whose lifelong sacrifices for Julie’s future might be derailed by the choices she’s made in her present.

Owen’s script navigates the thorny complexities of social mobility, working-class aspiration and intraclass conflict: while both teens were born and raised in Splott, Julie goes to a Welsh-speaking comp and owns a laptop, which puts her in a very different social site to Romeo, who is struggling even to afford nappies for baby Niamh.

The set is spartan: designed by Hayley Grindle, it is a black hole of sweeping greys, overhung by a flashing neon constellation, its geometric swirls flashing like comets’ tails. It seems to illuminate two very different futures: is it a prelude of Julie’s bright career to come, or merely the twirling mobile above a baby’s crib? Can we ever reach the stars, or even change our own?

Romeo and Julie is the perfect show with which to celebrate the Sherman’s 50^th year: small-scale and specific, yet sweeping and universal, which upends a classic and makes it anew.

Romeo and Julie is playing at the Sherman Theatre through to 29 April. Check the website for details on relaxed, captioned, BSL-interpreted and audio described performances.