Before Set Designer Linden Hogarth's backcloth of a high-rise office skyline, perhaps doubling as a sales figures graph, Emma's Manager, smart in an anonymous suit, sits on a swivel chair at a tubular steel desk adorned with an in-tray, an out-tray and half a dozen biros. Employee Emma, equally smart, perches in front of her through a series of 14 short appraisal interviews. Mike Bartlett's brief (65 minutes) but piercing drama takes aim at the prying of big corporations into the intimate lives of their staff as Emma is led oh-so-gently through the company's rules on personal and sexual relationships at work.

Director Lisa Friedrich creates an initial atmosphere of cagy disquiet from Emma lingering in the air. Caginess gradually melds into semantic ambiguity as meeting No. 2 circles around the definition of terms – romantic and perpetrated come under particular scrutiny – as by little increments the Manager ups the ante, demonstrating a prurience whose bureaucratic carapace contrasts bizarrely with its breathless content. Despite her sharing of gender with Emma, there's no sisterhood here.

"A substantial amount of eye contact... you put your hand on his inner thigh.... mouth to mouth kissing... your tongue in his mouth....."

Mr Bartlett shows slyly the process of Emma feeling compelled to absorb the evidence of this rummaging into every cranny of her life. Personal space ceases to exist independently from corporate entitlement, with the result that she herself begins to employ the language of the bureaucrat:

"We've been monitoring our relationship and have reached an agreed definition".

The first night audience of 26, no one seated more than five metres from the actors, sat rapt as the appraisal meetings slipped by, their tone veering disconcertingly between black comedy:

"You say the sex was good. [Your colleague/boyfriend] describes it here as excellent"

and creepiness as human relations are fed before our eyes through a sequence of rulebooks and conduct dossiers, the Manager iterating a mantra about her duty of care. Each meeting is carefully differentiated from its predecessor by Lighting Designer Adam Marshall's variation of colour and brilliance, and by sparingly-used music that quietly develops from the bland to something approaching the sinister.

So far, so much social and political drama. Then, of a sudden, around the interview No. 11 mark, Mr Bartlett throws down his sniper's rifle with a clatter, grabs a blunderbuss and we find ourselves fired into the realm of melodrama, a more superficially exciting place perhaps, but a less thoughtful one. Spoilers' convention applies here, but suffice it to say that the company's intrusion assumes proportions so monstrous that only a rank coward or ineffable fool – and Emma is neither of these things – could endure it for a moment. This is a pity since the drama's themes today assume even more importance than they did at its premiere in 2008. In those nine years globalisation has continued its inexorable mushrooming, and after Brexit employment rights are set to lose the protection of EU legislation and its courts.

As Emma, Sophie Stiewe has the difficult task of finding different ways of conveying puzzlement, affront, incredulity and incomprehension. If these adjectives are quasi-synonymous, Ms Stiew's playing of them cannot afford to be homogeneous. In the event, I thought she made a good stab at variety of reaction, and her dwindling into degrees of submission and depression as the wheel turns full circle was very touching. Cat White's silkily-spoken, nameless Manager was a fine study in administrative dissembling, a robotic wolf in sheep's clothing. Ms White cleverly conveyed the feeling at the end, when belatedly put under pressure by Emma, that this Manager was as much a corporate prisoner as was her victim.

This is a small-scale production that packs a hefty punch, the excursion of the script into something resembling sensationalism notwithstanding. Director Lisa Friedrich and her crew have combined with flair in its realisation, while her two actors demonstrate sensitivity, discipline and intelligence. Strongly recommended.