IN his programme notes, Theatre Mill director Samuel Wood writes how the final character in the York company’s site-specific productions is the site. The play serves the space; the space makes the play complete, he reasons.

After the Mansion House and York Guildhall Council Chamber, Theatre Mill have taken over another historic York setting, the Undercroft of the Merchant Adventurers’ Hall, a character “with a lot to say”, being dark, moody, sensual and mystical, according to Wood, who was drawn to its Gothic possibilities for a nocturnal drama set in Victorian London.

He and designer Becs Andrews set to working out how best to use the Undercroft, in particular the central pillars that could be both a boon and a bane. A traverse stage was ruled out in favour of three rows of seating on each corner, placed on an angle for the best sight lines. Yes, there would be moments where a character might be out of view, but the advantages far outweigh any disadvantages, the pillars being shadowy, gloomy, full of foreboding, whether in Dr Jekyll’s laboratory or on the London streets.

Theatre Mill utilise Nick Lane’s stage adaptation, premiered by Hull Truck Theatre and now given a fourth cast member complemented by supporting players in assorted cameos. The piece is both a thriller and a study of the duality of man’s nature, driven by Robert Louis Stevenson’s theme of man’s desire to conquer (the limitations) of nature through science.

Played by James Weaver, who reprises his Hull Truck role, Dr Henry Jekyll is blighted by physical disabilities, his left arm withered, his legs requiring the assistance of a walking stick, and he talks of not having long left. His brilliant mind is working feverishly as he seeks to change not only the face of science, but the world too.

In turn, Lane has changed the traditional representation of Hyde as repellent, physically deformed and broken. His Hyde, as portrayed by the handsome Weaver, is physically lithe, powerful, athletic..and as dangerous as ever under the influence of Dr Jekyll’s chemical concoctions.

He is all too intoxicating to Viktoria Kay’s Eleanor Lanyon, an Irish chanteuse invented by Lane in the absence of female characters other than prostitutes in Stevenson’s story. She is wife to David Chafer’s Dr Hastings Lanyon, decent but dull by comparison.

Weaver is tremendous in his Jekyll/Hyde role in a production with no fewer than 24 transitions that captures the struggle within as ego drives the man of medicine to the allure of dark deeds. Viktoria Kay handles three roles, three accents, with aplomb and has a livewire stage presence that is riveting; Chafer is kept busy with four contrasting roles while company regular Adam Elms is as engaging as ever, playing perturbed lawyer Gabriel John Utterson.

Andy Pilliner’s lighting, creepy incidental music and well choreographed, slow-motion acts of brutality all contribute to Wood’s production being a terrific theatrical experience.

The Strange Case Of Dr Jekyll And Mr Hyde, Theatre Mill, Merchant Adventurers’ Hall, York, until March 22. Box office: 01904 623568 or at yorktheatreroyal.co.uk