Yonni's 17 - a gay, Jewish Londoner. He's a criss-cross of contradictions and idiosyncrasies: dressed in streetwear, fascinated by science, a good kid with a Grindr account, who goes out on Friday nights and tries to observe Sabbath. He's confident in life and nervous in bed; a mummy's boy with a strong sense of independence.

Stephen Laughton's monologue, a favourite at this year's Vault Festival, is motored by character. It's not just that Yonni is as knottily complex as any of us, many different people in one, it's that his particular blend of incongruities, express something far bigger than himself: Judaism's place in today's world.

Run recounts the course of a single summer - a 17-year old's summer, when school's over and life seems to stretch out ahead of you into infinity. It might be the moment any of us are most alive - so present to each day's possibilities, so full of future potential. Laughton's writing catches all of that, and Yonni is flushed with all the immediate feelings of his first love, even as his thoughts race off to the ends of time and space - to plants, to faith, to nature, to history. He is, like the best 17 year-olds, full of wonder.

Yonni met Adam at camp - "Jew Camp," they call it – and, after slinking into one another's beds at night, both got themselves expelled. If there's a tension between sexuality and faith, Laughton's drama doesn't depend on bringing that clash to a head. Run's not a 'God or Guys' play. It's more complex: an examination of inter-sectional identities.

That particular tension fits into the wider dissonance between orthodox Judaism and contemporary life. Yonni's an utterly contemporary kid with an age-old religion. His clipped London tang slips into ancient Hebrew prayer. His personal tech jostles with Sabbath laws that, strictly speaking, prohibit adjusting electrical appliances. Each Friday night, Yonni ducks under the duvet with his iPad. At his Golders Green deli, Yonni's still the six year-old out shopping with his dad. On Grindr, not so much. Run conveys the oddities of overlapping identities with real delicacy.

Tom Ross-Williams is superb in the role, never trying to smooth out the different sides of this unassuming, engaging teenager, but rather letting moods swing and interests shift. It's a performance that's comfortable with inconstancy - no mean feat - held together by a contagious energy. An hour in his presence is an enlivening thing, and he moves beautifully, punctuating the text with religious rituals set to rhythmic beats.

Though it's narrative isn't always entirely clear, its plot skipping a key beat or two, it spins an idea into something urgent. When Yonni's the victim of an anti-semitic attack, crossing London late one night with his kippah on, the violence is both present-tense and timeless at the same time. Each punch lands, each hurts and hurts now, but each connects to a long line of punches thrown in the same vein. It's a stunning encapsulation of violence couched in prejudice - something both singular and manifold; its victim, both an individual and a symbol or a representative. Neither should diminish the other. An appalling assault is all the more appalling because it fits into a pattern - and one that has no place in this day and age. That such anti-semitic attacks are on the rise - it is, says Yonni, "super fucking shit" to be a Jew in Britain today - is the most anachronistic thing of all.

Run runs at the Bunker Theatre until 1 April.