Spur of the Moment, Royal Court Theatre Upstairs

"She's just a kid," or so runs the mantra that weaves its way through Spur of the Moment, the Royal Court premiere from newcomer Anya Reiss, who was "just a kid" - well, 17 - when she wrote the play. How, then, to explain an exceedingly sharp, smart piece that will invite comparison with another recent Court find, Polly Stenham, who was a comparative "oldie" by the time she pitched up at Sloane Square? As ever, it's nigh impossible to calibrate talent with numbers of years old, beyond pointing out that Reiss possesses the former in abundance even if she is self-evidently lacking in the latter. As the great Tom Lehrer once remarked, riffing on this very topic: "When Mozart was my age, he'd been dead five years." If this play and the director Jeremy Herrin's customarily expert treatment of it are any indication, Reiss has a long and happy playwriting career ahead.

The terrain overlaps somewhat with that of Stenham, not least in a staging that points up the extent to which Herrin is as acute a director of young, unseasoned talent as I have ever come across. Like Tusk Tusk, the Stenham play first seen in this same studio-sized space (seating capacity: 85) in March, 2009, Spur of the Moment occupies that extended fault line known as adolescence, or just before. Your body is changing and, with it, so are your obsessions and hopes and fears. Indeed, it's one of the neat tricks of this play that it starts in the world of High School Musical and Hannah Montana, with a hilarious detour toward Harry Potter, 

• Spur of the Moment is at the Royal Court Theatre until 14 August.