Readers will have noted that the classics cultivate a certain sinister duality in the minds of adapting producers. On the one hand they’re drawn to the immutable greatness of the material, the enduring themes and characters that have sucked off the imaginations of generations. On the other psoriatic hand, with its bleeding lesions and ugly fungal nails, there’s the desire to reinvent, to repurpose the material into something more palatable to the creative team’s politics and sensibilities. The subtext is that great though the original work is, it can always be more.

The latest Zero Mostel to second guess a genius is Nick Lane, whose production of Robert Louis Stevenson’s 1886 novella, contorts wildly, flirting with the text one minute, storming off to have its wicked way with the audience the next.

One senses Lane thought the dusty original to be a bit of a sausage fest and somewhat dry for the provincial theatre crowd, not to mention rather violent. So in place of what’s written, this sanitised riff introduces a love triangle sub-plot, just to heighten Jekyll’s tragedy (which assumes it’s in some way wanting) and underline his disservice to rational but boring friend, Hastie Lanyon. The change shifts the focus from Hyde’s violent exploits and the warring facets of the not-so-good Doctor, to his problematic relationship with Lanyon’s comely wife – a newly invented Irish musical hall entertainer whom, in the interests of parity when it comes to gendered explorations of repressed desire, comes for Jekyll’s genius but stays for the ravishing, beast-like multiple murderer he becomes.

This works fine as a thematic extension of the source material – after all it’s a story about doubling, but the execution privileges melodrama over the tale’s signature creeping gothic horror. And in keeping with the milquetoast creative instincts on display here, the brutality of Hyde is softened, used ill-advised devices, better suited to schlock cinema, like simulated slow motion, which blunts (and infantilises) what should have been the story’s moments of raw terror.

It’s as if Lane, determined to “correct” for Stevenson’s lack of interest in female characters and fascination with unregulated impulse (memorable affronts to society like Hyde trampling a child), couldn’t work out how to utilise stagecraft to creatively, inventively, depict Hyde’s rapacious, unbidden id in way that didn’t require a nightly washing down of the boards. The killing of Danvers Carew, for example, is given such a camp aspect, it’s less an immediate and chilling act of murder, more a playground re-enactment.

Jack Bannell’s performance in the title role is committed, and he’s successful at modulating his voice and altering his physicality, but for all that, he doesn’t quite sell the character’s profound transformation. In part, that’s because he’s simply too matinee for this shit. How could the shapely songstress be attracted to him otherwise? But Stevenson’s Hyde, embodying predatory sexuality and violence, wasn’t burdened with being a love interest, so was free to appear monstrous – beyond, indeed, the ability of others to accurately describe him, implying someone anthropoidal, unlike any off the shelf type. Bannell looks like he’s playing the lead in a play called Dr Decrepit and Mr Bad Boy, which though unsettling, is not quite the distillate of knowing inhumanity that’s cut across a century and change.