Two sisters, a knight, a miller, and a blind harpist. Such is the cast of Tony Harrison and Harrison Birtwistle's Bow Down, their 1977 music-theatre piece currently being toured around the UK by The Opera Group. It's an elemental, mythic piece, but also a testament to the endless capacity for novelty that old, grim folk tales like this have.

And it's also an uncommonly clear example of artistic interdisciplinarity; young musicians, including a flautist and an oboist, perform alongside young actors – but all seven are involved across a range of artistic activities. The musicians speak and move along with the actors, and the actors play a variety of percussion instruments and whistles. Everyone sings a bit. There is a sense that nobody is fully within their comfort zone, and this adds to the performance a certain trepidation bordering on distrust, which greatly enhances the dark tale told.

This was a fascinating meeting of media, although it seemed to me that the theatrical element to the piece eclipsed the musical one most of the time. This isn't meant as a criticism of Birtwistle's involvement by any means; rather, in fact, it is highly impressive that his piece shows such compositional subtlety. While the music is a key constituent element of the work, it's also an admirably transparent vehicle for the narrative. Always atmospheric and evocative, the music provides a sort of rhythmic grid of sounds such as shovels scraped on stone, falling metal chains, and pipes and whistles. The sinister beat of the drum is never far away, and Tony Harrison's meticulous, rhyming, folklorish text is recited rhythmically at all times. But all the sounds gel together to the cause of telling the story, and it's the grim, graphic, murderous tale which lingers in the mind.

It's a well-told story too, which The Opera Group's artistic director Frederic Wake-Walker has clearly directed with care, and Anna Jones' set design is also impressive with its sinister mangled roundabout and clumps of soil. In London last night (as part of Spitalfields Music Summer Festival), the carefully chosen venue also added hugely to the real sense of atmosphere evoked: Village Underground in Shoreditch is a cavernous, intimidating space which suited the piece. The acting was strong; Anita-Joy Uwajeh and Yolanda Mercy as the two sisters worked well together, capturing their malicious rivalry effectively, and Simon Kent and Thomas O'Connell were a laddish pair convincing enough to pull off the lighter tone of their roles without breaking the spell. Rehana Browne (flute) and Mana Shibata (oboe) not only played their instruments involvingly, but also gave impressively confident dramatic performances. Most impressive of the cast was Benjamin Mahns-Mardy, the blind harpist, whose brilliantly fevered delivery of two completely incomprehensible speeches was a particular highlight.

Mahns-Mardy's biography suggests that he has the most mixed background in terms of artistic discipline, and while it's a shame to point this out, his having experience in both music and theatre really showed: his musical contribution was very strong (he was in charge of the all-important drum), and he was a gripping presence on stage as well. While encouraging performers to break stylistic boundaries is part of the concept behind multimedia works of art such as this, it perhaps points to an inherent conceptual flaw in the enterprise when the most engaging performer is the one with the most rounded CV going into the project. It was possible to pick up on a lack of musical or theatrical experience from the other cast members, and – especially given the impeccably high production standards – this did come across as a slight problem.

But that said, the strength of this production is the storytelling, and it's an enthralling account. The hour zips by, and the narrative is compelling. Providing a dark, sordid, primal account of a folk tale is not an idea unique to this piece, but Bow Down's inventiveness and originality of medium singles it out. This is a rare chance to catch this important music-theatre work, and – assuming its next venue on tour at Latitude Festival suits it as well as this one – it's well worth it, both to hear and to see.