There is no plot in Anya ReissSpur of the Moment, just the raw, jangling sound of a 12 year-old girl, Delilah Evans, developing a crush on a 21-year-old “hot” lodger, Daniel Mast, to the amusement of her friends and the annoyance of Daniel’s girlfriend, Leonie, who comes to stay.

Delilah’s parents, Vicky and Nick, are tearing each other to shreds, bickering and fighting over tea and coffee, every domestic incident cast in the shadow of marital break-down: Nick has had an affair with his boss, “an older woman,” (he’s in his early 50s) and has been sacked.

Reiss, another talented product of the Royal Court’s Young Writers Programme, is studying for her A-levels and wrote the play when she was seventeen. She has written down exactly what she has heard, translated the rhythms and backchat of everyday life into bitty but well-expressed dialogue that achieves its own momentum.

With her three school friends, Delilah plays out the public side of “having a boyfriend” as they listen to snatches of High School Music and other pop tunes, and these passages capture exactly the sort of conversations you hear every day on the top of a bus: raucous, rude, competitive and a bit frightening.

And the parents’ squabbling has the same quality of having been overheard: Sharon Small and Kevin Doyle play with the right sort of selfish edginess, glossing over the callowness of the writing with the skill of their technique. Young Shannon Tarbet makes an accomplished debut as Delilah, and James McArdle as Daniel finds himself drawn into a dangerous flirtation on the eve of the girl’s thirteenth birthday.

Has director Jeremy Herrin discovered the next Polly Stenham? Impossible to say. But Reiss shows every sign of bridging that gap between a sort of “youth theatre” automatic writing and a structured drama. The scene where the household sits down to watch the Batman movie, The Dark Knight, with the tensions and resentments eddying around the room, is sharp and very funny.

Much of the surprise of the play comes from the overbearing proximity of the characters to each other on Max Jones’ split-level setting, with Delilah’s friends even, at one point, trooping into the living room through the refrigerator; and then trooping off by the same route.