The finer subtleties of Bryony Lavery’s Tony-nominated play are here bled for shock and effect, but there is only so much musical blare and spluttered swearing that one cramped audience can take. An impressive initial sense of unease soon wears off, and strands that should stitch together the tripartite plot – intertwining the lives of a missing child’s mother, a convicted paedophile and murderer, and an academic investigating the psychology of serial crime – generally work to confuse rather than clarify. And yet, two surprisingly controlled central performances, from Phoebe Garrett and Michael Muncer as the controversial academic and the criminal, hold the audience’s attention, and there are moments of real interest to be found here.

Expressions of anguish are dealt with well, and brief moments of contemplation are accommodated by the mother’s understated performance. The climactic lecture provokes some intriguing medical and moral dilemmas, and meditations on the term ‘forgiveness’ prove fruitful. While a bold stab is made at this depraved and solemn subject, what the production makes up for in energy, it sadly loses in nuance.

Sweet Grassmarket, 0870 241 0136, until 30 Aug, 7.15pm, £7.50 (£6.50).