'In the Penal Colony', Linbury Studios, London and September Songs, Ikon Gallery, Birmingham

Kafka's brave new world: Three grey men, silent torture ... and a wisp of The Stylistics

Kafka had yet to leave Prague when he wrote his colonial fantasy In the Penal Colony. Beguiled by exotic travel memoirs and boys' adventure stories, he would actually never leave Europe.

There is little sense of place in the narrative. While the apparatus that dominates his sado-masochistic story is imagined in fetishistic detail – the glass harrow, the leather straps, the felt gag, the cogs and wheels that determine which sentence will be inscribed on the prisoner's skin in the course of his 12-hour execution – its location remains vague: hot, remote, non-Western. There are only three characters. The Condemned Man is a mute indigenous cipher, unable to understand the language in which he is being discussed or the torture to which he is about to be subjected. The Officer is the last adherent to an ornate ceremony of justice without trial, the Visitor an ambivalent witness.

Ambivalence is eradicated in Michael McCarthy's taut, angry Music Theatre Wales production of Philip Glass's adaptation, getting its first airing in the UK. The story unfolds in a bare, grey space, with a bare, grey table, a bare, grey chair and a floor-to-ceiling ladder the only dressings in Simon Banham's design. In Rudolph Wurlitzer's libretto, the Visitor (Michael Bennett) experiences Conradian revulsion and contemporary smugness ("In my travels I have learned to respect each country's customs, no matter how strange"), while the Officer (Omar Ebrahim) fleshes out the character of his former commander, the late inventor of the apparatus, as engineer, judge, chemist, architect, cook and draftsman. This Waughian biographical flourish has little effect on the narrative. Neither does the Officer's brief aria on homesickness, or the faint but firm twist in tone that makes Kafka's conceit read like a protest against non-interventionist foreign policy.

The execution must take place, whoever is killed. When it finally happens it is realised with shocking economy. Even so, it's hard to feel anything more than a ripple of disgust. Though McCarthy tries to imbue each character with humanity – Gerald Tyler's performance as the silent Condemned Man is strong, while Ebrahim wins this year's Mad, Staring Eyes in Modern Opera Award – Glass is uninterested in conventional characterisation. Voice registers aside (Bennett is a tenor, Ebrahim a baritone), there is little to distinguish the parlando of the Visitor and the Officer, although, pace Mark-Anthony Turnage, I thought I heard a wisp of The Stylistics' "You are Everything".

Both voices are amplified, though not as consistently as the instruments. Brilliantly played by the ensemble under Michael Rafferty, the 80-minute score for five string-players has a narrow remit, breaking a steady pulse into hiccuping quavers, looping arpeggios, threads of harmonics, neat pauses in which the metallic hum of the unseen apparatus fills the void. Were it not so very similar to Glass's other work, I'd assume it to be imitating the apparatus's motion: an extended piercing with curlicued variations. Like the Officer, the listener has to submit to the process.

Last weekend, much of Birmingham became a Freshers' Fair for the arts. While Broad Street vibrated to the sound of massed salsa drums and Birmingham Opera Group recruited cast-members for Les Noces, Birmingham Contemporary Music Group's September Songs project took Howard Skempton's cool, rapt chamber music into the Ikon Gallery, using abstracts from the 1970s as counterpoint to Skempton's miniatures for strings and percussion. This was an all-ages, all-comers event; you could wander freely, listen for as long or as little as you liked, even join in. Watching violinist Alexandra Wood respond to two small boys improvising on violin and cello reminded me of why playing an instrument is called playing. Skempton has a distinctive, clear and calm voice. You need know nothing about enharmonic key changes to be enchanted by the fractured melancholy of Piano Trio (1993), or the heat of Arcade (1997), while listening to his newest work, Whales Weep Not!, for mezzo-soprano and bell lyra, was like looking into a sea shell. Premiered by Loré Lixenberg and Julian Warburton, this intimate, wonder-struck tracing of DH Lawrence's poem is one of the most beautifully crafted works I've heard.

'In the Penal Colony': Haymarket, Basingstoke (01256 844244) to 21 Sep