Chronicles of Long Kesh, Assembly Rooms @ The Mound, Edinburgh

A bunch of IRA prisoners, holed up in the disgusting conditions of Long Kesh during internment without trial in the 1970s and 1980s, punctuate their grim memories and protestations with Motown hits.

This ironic concert party, performed a capella with a design of inter-cutting rostra serving as an improvised drum kit, makes a pleasant change from smearing their cells with excrement and going on hunger strike. Martin Lynch's rivetting play for the Belfast-based touring group Green Shoot enlists an audience as witness to history by embroiling them in the dynamic of super-charged live performance. It's this year's Black Watch.

Standing ovations have become habitual on the Fringe, but the one at Chronicles is both earned and heartfelt; the actors have brought us to fever pitch with their intensity and virtuosity.

None of the prisoners is innocent of sectarian violence, but each is seen as part of a tapestry in society that has been torn apart and left to rot. Wives complain bitterly about politics coming before family life. The prisoners take orders from outside, refuse to wash and slop out, plan a "great" escape.

Suddenly the Republican hard men – five, including the remarkable actress Jo Donnelly – start belting out a Loyalist marching song, demonstrating the accident of religious affiliation.

Lynch's male quartet, played with uniform ferocity and guile by Chris Corrigan, Marty Maguire, Marc O'Shea and Andy Moore, contain elements of real prisoners, but all stand alone as well-delineated characters, as does Billy Clarke's tortured prison officer, another victim, in this compelling take on a tragic era, stained with hindsight.

To 30 August (0131 623 3030)