It is not quite a Dylan-goes-electric moment, but for the first time in two decades neither of the plays being staged by Bard in the Botanics, the summer repertory company, is by Shakespeare. In a mini-Victorian season, you can see The Importance of Being Earnest on the outdoor stage, while here in the 150-year-old Kibble Palace glasshouse Jennifer Dick has adapted Strange Case of Dr Jekyll and Mr Hyde.

Notwithstanding the change of author, Dick gives the Robert Louis Stevenson thriller a Shakespearean sense of oratory. Our point of entry is the lawyer Gabriel Utterson, a narrator who eases us from the prose of the novella into a stripped-down drama for three actors. Played by an excellent Stephanie McGregor as confidant and conscience to Adam Donaldson’s arrogant Dr Jekyll, Utterson speaks in the vivid language of a storyteller, all lengthy sentences and iambic rhythms, calling on the breath control of an experienced classical actor.

The approach suits the heightened gothic melodrama and, along with Sam Stopford as a weaselly Mr Hyde, the performers create a tense three-way struggle.

All adaptations of this book wrestle with the challenge of making explicit what Stevenson only implied. For the purposes of the drama, Dick allows Jekyll and Hyde to argue with each other as if they were independent characters rather than two sides of the same coin.

Being less interested in the mechanics of the transition from respectable doctor to fun-loving murderer, she focuses on the moral implications of separating the good and evil sides of human nature. Blinded by his own ambition, the upright Jekyll ends up as degenerate as the hedonistic Hyde. By contrast, Utterson reveals a sense of right and wrong that goes beyond the lawyerly. Behind her shock at her friend’s experiments is a deeply felt plea for moral responsibility.

• At Glasgow Botanic Gardens until 29 July