There's a lovely reading on YouTube of Dylan Thomas's short story Just Like Little Dogs. The text unfurls on the screen as the voice of – I think – Anthony Hopkins speaks the words. If you haven't come across it yet, it's worth Googling. But although Frantic Assembly and National Theatre Wales have taken Thomas's text as their inspiration, the performance they have created with their nine-strong cast is only tangentially related to the rain-sodden tale of young men mooching around Swansea of a chilly evening.

What is Thomas-like about the production is its energy, visceral as blood beating through veins, sharp as starlight on a dark night. In the centre of the space a shabby sitting room is torn apart, separating the pair within: white-haired matriarch (riveting Siân Phillips) and edgy adolescent (palely interesting Darren Evans). Now he's surrounded by hoodies on a black rubbish-sack lined road. An ambush? No, a testosterone-fuelled dance that mutates into a sassy mating game which plays out its various moves with furious, fleshly intensity for the rest of the evening.

Music, choreography and English-language text are dynamic. Gentle interludes are well-placed but, with the exception of a breeze-soft Welsh lyric sung by Phillips, given only to male introspections. This is disappointing. The female roles are nonetheless strong and convincing, while the finale – in which Phillips is transformed into an angel-cum-human maypole - is a sublimely silly yet genuinely life-affirming theatrical coup.

Good as everything and everyone else is, it is Phillips who commands the show – and this is the greatest strength of the conception of the piece. Her understated presence counterbalances the wild exuberances of the teenage characters that surround her. By reminding us that youth is a thing that does not last, she induces in us a Thomas-like compassion for this turbulence of teenage self-obsession.