By her own candid admission, Kate Mulvany’s Medea bears little resemblance to the Greek mythological one. Mind you, the original Medea was married to Jason and so is the latest. Jason sounds like a plausible name for the son of a baby boomer, anyway. But instead of Mermeros and Pheres, we have Leon (Joseph Kelly) and Jasper (Rory Potter). Two more naturalistic actors, of any age, you’d be lucky to find. They are finds. So much so that I reckon it must’ve been intimidating, even for an actor of Blazey Best’s calibre, to play their murderous mum.

Mulvany’s Medea (not so much adaptation as a script “divinely inspired” by Euripides’ play) isn’t so much focussed on her husband’s betrayal. After all, betrayals are everyday occurrences. Her poisoning of her children in this case isn’t part of an orgy of revenge, but a glowing example of the protective maternal instinct and unfathomable depths of a mother’s love. Jason is coming to get them, presumably because, as in the Medea of old, Mulvany’s modern Medea has sent Jason’s “other woman” a poison package.

Beyond this scenario, the character of “our” Medea is somewhat indistinct; though there’s a clue in one of the boys’ comments on their mother’s replacement (“I think she’s nicer than mum”). Like so many myths, Medea took time to develop and changed, in the manner of Chinese whispers, over time, so that many variations on the theme are extant. At least one has Medea as a witch, whatever that means (perhaps it relates to her penchant for potions), so maybe this is what’s being intimated in the dialogue.

This co-production of Belvoir (Downstairs) and Australian Theatre for Young People certainly represents an original, imaginative idea, on behalf of Mulvany. And a superlative realisation, on behalf of director (and co-writer) Anne-Louise Sarks and her tainted team. The dynamic duo have had the good sense and humility, too, to ask the boys and, indeed, all the cast and crew to share stories of childhood, so that they might succeed in drawing a true and credible picture. As Mulvany admits, “behind every word of this text there’s a water fight, burping contest, fart joke, piggyback race, sour bomb, leap off a balcony and into a pool”. She cites the real tragedy of Medea is not mere loss of innocence, but the theft of it, by adults.

When we walk into the theatre, we walk to the boys’ bedroom, in which they’ve been incarcerated, while their parents indulge in yet another argument. Mel Page has observed it faithfully, from cheap, blue carpet, to unmade beds and toys strewn everywhere. I particularly liked the baby doll with an arrow in it. They must amuse themselves but, in between, we learn of their anxieties as regards their futures. They muse, for example, on how long it takes for parents to work things out, deciding it takes an interminable time; possibly as much as a couple of hours! As kids might, they seek (especially the younger Jasper) to salve their worries through imagination. Dad’s reputed to have a mansion and Jasper’s dead keen to live in one.

For a 12 and 13-year-old, it’s nothing short of astonishing how easily these young actors carry their lines. There’s a lot of them, too: they take up much, or most, of the 75 minutes on stage, alone. There are points at which the script is in range of dragging its heels a little, but the charm of the boys brings it home without any real lulls or flatspots. As much as the actors deserve credit for this, so too do Mulvany and Sarks, for much of that charm is intrinsic to the fastidiously wrought script.

Meanwhile, the sense of what’s happening on the other side of the locked door they occasionally press their ears up against is menacing; downright gripping, in fact. We can feel the tension escalating and this is underscored every time Best appears: the time-bomb latency of her containment upsets our equilibrium. Her control is chilling, threatening and, finally, tragic. There are two essential strokes of genius in the work. One is directorial and lies in the counterpoint between the timeless idyll of make-it-up-as-you-go-along childhood games and the urgency of Medea’s concerns. The other is the mediation of overwhelming tragedy with everyday humour; the very stuff that has enabled people to survive times and situations as horrendous as the Holocaust.

There’s another thread woven through the play, insofar as the boys’ concern over something bad, but unspecified their mother once did. Between them, they speculate it might’ve been something as heinous as smoking. One wonders if there’s an intention to visit philosophical ideas, such as whether or not a kind of karma, or poetic justice might prevail, such that children pay for the sins of their parents, just as we all pay, societally, for the sins of our collective forefathers.

But, anxious as it is, there are times in which we can lose ourselves in the boys’ games as easily and willingly as they do. It’s a fool’s paradise. And wouldn’t we all like to live there, sometimes?

Benjamin Cisterne couldn’t have kept his lighting design more elementary, yet it’s devastatingly effective, working hand-in-glove with Page. When the lights go out, we see the stars. When it gets right down to it, stars are dust. And so are we. Mulvany and Sarks’ play has the other vital ingredient that makes astral objects glow. Heat. While the boys are chilling in their room, the off-stage action ramps up to fever pitch. If Euripides was alive today, I reckon he’d jealously mutter, over a cleansing ale, “why didn’t I think of that?!”

If there’s anything to criticise (and these theatremakers haven’t left much), it’s that some of Blazey’s lines are a little trite and it’s only her skill that enables one to look the other way. But all in all, this Medea could be the mother of all of ’em.

The details: Medea plays Belvoir St’s Downstairs Theatre until November 25. Tickets on the company website.