Based on Kafka's 1914 short story, Philip Glass's chamber opera explores the circumstances of a condemned man awaiting execution. The Officer (Omar Ebrahim) believes in upholding the old methods of torture and killing; the Visitor (Michael Bennett) is appalled by what he sees but unable to intervene as the inevitable occurs. This is a tough but worthwhile listen, using the same cast as Music Theatre Wales's 2010 staging. The familiar oscillations of Glass's score, skilfully played by a quintet of strings with electronic noises off, are put to intense, inventive use. If singers and players at times sound raw, it's fitting for this allegory of cruelty and the moral dilemma of being a bystander.