At the very beginning of Ontroerend Goed’s exhilarating display of wild youth, lockstep conformity and blistering confrontation – adolescence, in other words – a draconian old maxim is turned on its head: the children are heard but not seen.

Assailed by throaty yells from offstage, menacing chants that erupt and subside, the audience faces a cacophony that would be unnerving enough even if it didn’t drown out the safety announcements. The unlikely event of an emergency has never seemed more likely.

This, however, is a confrontation that breeds excitement. In a neat irony that will have escaped absolutely nobody, the Ulster Bank Dublin Theatre Festival programme concludes its enthralled description of the production’s youthful energy with a sober caution: “Not suitable for children.” Depending on how you define children, this could have rendered half the cast ineligible for attendance, which would have been a pity, because it’s a theatre of them, by them and potentially for them.

Included under the festival’s documentary theatre strand, the reality stance is a thin ruse. Director Alexander Devriendt has assembled thirteen genuine Belgian teenagers to perform genuinely as themselves, but just as those early yelps and ejaculations acquire the rigour of an orchestra’s warm-up, each teen is an instrument ready to obey the structure and patterns of artifice and design. It isn’t child’s play. A nerveless teenage girl, Charlotte De Bruyne, emerges to address the audience alone in tentative English (“This show is about… adolescence? Is that the right word?”) which leads to a much less hesitant implication of the audience in the role of decrepit voyeur, before an unanswerable taunt, “We can start over again.” The ensemble briskly emerges and all hell breaks loose.

At least it seems to. Taking to a line of rickety wooden seats, a procession of teens in clothing for which there must be some sort of an explanation, begin flirting, fighting, joking, setting fire to Barbie dolls, fighting some more, collapsing, screaming, chalking messages on the floor, spitting cascades of water over each other, playing inscrutable sexual games with rubbish bags, forming alliances and falling apart. Just at the point when you think these kids need to be taught some discipline, an alarm sounds, the music halts, and the entire cast clean up with the harried precision of army cadets. The scene begins again, identically, and the chaos is revealed as choreography.

Teenagers, like the poor, will always be with us, their sudden mood swings and rising/falling maturity index explored in everything from the opening scene of Shakespeare’s Henry V to every scene in 90210, yet few shows have captured their tormented spirits, their dangerous desires and rude awakenings, their twin impulses to rebel and conform, as archly as Once and For All... Its makers may resist the notion that they are depicting something besides reality, and its performers continually shoot down the tags “actor” and “character”. But as the scene is repeated in ever more stylised variations – first a ballet, then a rave, now delivered with automaton dispassion, now blown up into startling parodies, here a Brady Bunch of mock family cheer, there a Velvet Underground of heroin chic – each sequence becomes an ever more elaborate act. By extension, every adolescent pose within it becomes just that, a pose. If this is a documentary, it is documenting an age of performance. Should anyone maintain that work of such precision, repetition and seemingly spontaneous play is either unmediated reality or a genuinely new form of theatre, there can be only one retort: oh, grow up.

As with last year’s post-dramatic display of unsupervised Belgian youth, Victoria’s That Night Follows Day, a shiver of exploitation accompanies the obsession with their fervency, their sturm und drang und funky haircuts. That Beckettian alarm, immediate subjugation and unspoken rules implicate the director, but the viewer as well. As the energy of the performance spills into the auditorium, though, and we are encouraged to shout with them, before rampaging teens depart the stage to streak their audience with lipstick and catch them in a crossfire of spray confetti, the kids seems to be in control.

“Everything has been done before,” says Charlotte, “but not by me, not now.” The show sweeps us into the exhilaration and anxiety of endless possibilities, where every rite of passage is still a fresh discovery. Watching the teens return from a standing ovation to dutifully clean up the mess they made put their youth in a light both reassuring and slightly saddening. They’ll grow out of it eventually.