This engaging but hurried adaptation of Philip Pullman’s 1985 novel packs in a handful of clever tricks and plenty of visual style, but is frustratingly inattentive to the storytelling. The tone is struck by what, in Fringe terms, is a truly impressive set: with densely-packed buildings and brightly-lit windows, it’s perfectly evocative of the crowded streets of Victorian London.

Into this maze steps Sally Lockhart, Pullman’s popular protagonist, who we learn – in a breakneck gallop through the back-story – is the reluctant ward of her comically misanthropic aunt. There’s an injection of energy when Lockhart meets photographer Frederick Garland, and together with Frederick’s sister and a likeable office boy, they set off to untangle the mysteries surrounding her father’s seemingly accidental death.

Much of the storyline is communicated through letters, and in these segments the show displays a particularly well-crafted elegance. The fundamental technique – having the letter-writer walk on to speak their words aloud – is a familiar one. But each letter signals a subtle change in tone, with an ethereal quality to the performance emphasising that we’re now seeing a scene rooted in the past. The occasional and brief inclusion of shadow-puppetry felt like an afterthought, which is a shame, because the few instances we did see contributed further to the play’s distinctive imagery.

But they career too quickly through the story; I just about managed to keep on track, but I always felt I was one moment’s inattention away from irredeemable confusion. Humorous lines are often lost in the flurry, and minor characters are offed with undue haste. Worst of all, the mysterious puzzle we’re set at the beginning – a riddle which points to the titular ruby’s hiding-place – is solved towards the end in the blink of an eye; they should tease us with relish on their way to that solution, not blurt it out in a fit of eagerness to push the story on.

The quality of the acting does vary, but key moments work well, especially in scenes involving “the terrible power of opium” and its capacity to break the human soul. There are numerous flaps and cupboards hidden around the set, which open out to evoke a variety of scenes; and there’s some nice use of hand-held lighting too. The children in the audience seemed to enjoy the spectacle (“it was really scary,” one said with delight) but it’s hard to imagine that they followed the detail of the plot. And for all that it’s just 31 years old, the storyline – with its maharajas and triads and focus on the otherness of Asia – feels oddly dated now.

Overall, this is a creditable effort from the youthful Reprint Productions, but it really wasn’t sensible to compress such a complex story down to the space of an hour. Lesson learned, I hope – and with a more manageable script, their eye for imagery holds plenty of promise for years to come.