Ever wondered what that kid is doing? The one you pass on your way to work, the one lingering at a bus stop with nowhere to go?

Well this is the subject of Boy, a powerful new play by Leo Butler that eloquently tackles the problem of growing up in London with no real family, friends or prospects.

Flicking through the programme beforehand, alarm bells were ringing. Butler has been around for a while, notably finding acclaim with 2001’s Redundant at the Royal Court.

Yet Boy has suspiciously undergone 10 rewrites over five years; it features a massive 27-strong cast, and a stage that rotates in the round via a long, gimmicky-looking conveyor belt.

It all reeked of over-ambition.

But from the opening scene of Liam, a 17-year-old school dropout from south London, agreeing himself into an unnecessary STI check, the authenticity of Butler’s language shines through.

Played superbly by Frankie Fox on his professional stage debut, Liam is a recognisable bundle of teenage confusion and ‘yeah but no buts’.

As we follow him on a Mecca-like journey to Sports Direct, however, you begin to realise that with absent parents and no friends to speak of, his eagerness to connect has sadly left him like emotional putty in the hands of a merciless city.

And indeed, director Sacha Wares has made London swirl with detail. From the language of schoolgirls at a bus stop (“You’re not on Twitter? You’re such a lying bitch!”) to the drones of oyster card machines and building works, it’s a world you recognize intimately, but through the fresh, fearful eyes of our young wanderer.

It’s not perfect: the set design by Miriam Buether is technically magnificent, but too distracting at times, especially with the use of some baffling invisible chairs.

Nonetheless, this is a rich, poignant work, which will make you think twice before crossing the street.

Boy is at the Almeida Theatre in Islington.

Rating: 4/5 stars.