Metaphorical resonance threatens to drown out narrative in Joe Penhall’s three-hander. Ostensibly a family play with a young son caught up in his parents’ battles, Haunted Child makes no secret of its real purpose. It shows the colossal tussle between a broken society and a new world order.

Penhall is open to accusations of over-directness and many will prefer their bitter pills better disguised, but there’s no denying the play’s forceful urgency.

It starts with a child’s midnight existential crisis. Convinced he’s heard a ghost – possibly his father’s – in the loft, Thomas darts downstairs to his mother Julie (Sophie Okonedo). “If we’re just going to die anyway - what’s the point?” He is answered with a hug.

In fact, Dad is not dead, but disappeared. Douglas (Ben Daniels) soon turns up, bedraggled and shivering, having converted to some cultish pseudo-scientific spiritual system. He dictates a credo to his son. He chants, induces vomiting and starves himself, renouncing pleasures and proclaiming the “need to look for an alternative.”

Needless to say, Julie, faced with the everyday pressures of child and income, hasn’t got time or patience for what seems to her nothing but a mid-life crisis.

There are a swirl of potent questions here: Can a marriage survive one party’s identity overhaul? Are we responsible for our beliefs? Should children be raised to question or to accept? Penahll’s skill is to make both spirituality and practicality well-matched opponents: equally necessary, but equally selfish.

However, the narrative is transparent: where Julie represents a materialist status quo, Douglas is the alternative with unfledged answers. On fixing the radiator, he declares: “The thing about these old systems is the valves go.” These are old tricks: the unkempt house, a symbol of a broken society; the son, who leans towards his father and sees nothing odd about his behaviour, is one of our future.

Jeremy Herrin turns this into advantage with an extraordinary production that combines the robust thinking of new writing with the tonal attention of devised work. Slow, heavy and mournful, his staging has a devastating preciseness. Images tumble out of it. A banana momentarily seems a microphone for Douglas’s breakfast speechifying.

Daniels and Okonedo are astonishing, pulling off a blunt style that, in the wrong hands, can look like bad acting. Daniels, who finds hints of Julian Assange in Douglas, is captivatingly intense, embedding tai chi into everyday behaviour. Okonedo is more easily heartfelt; earthy, emotionally drained and – most of all – urgent.

That quality is Haunted Child’s best and, in the final image of the torn family hugged together while the ceiling of Bunny Christie’s restrained design lowers, Penhall’s message rings clear and strong: the old system’s valve is going and we need to find an alternative.

- Matt Trueman