First seen at the Hampstead Theatre in early 2010, David Greig's intelligent and entertaining new play makes a very welcome addition to the offerings at the Swan Theatre. In association with the National Theatre of Scotland and Edinburgh's Lyceum, the Royal Shakespeare Company has only a short run of performances of what is a very assured and interesting piece of new writing.

Greig uses Macbeth as his starting place for a thoughtful examination of the effects of invasion and regime change on both conquerors and the conquered. Although never made explicit, he invites the audience to view modern conflicts such as Iraq, Afghanistan and the Balkans through the filter of the struggles for the Scottish crown after Birnam Wood has come to Dunsinane.

He is able to use language to bring both worlds together brilliantly – particularly through the character of Malcolm (Brian Ferguson) who is very much an equivocating modern politician trapped by the inevitable problems of his seizing of power.

Central to the play is the towering performance of Siobhan Redmond as Gruach – the widow of the deposed tyrant king. She lights up the stage with an intensity that almost shimmers with anger and power. If there is a flaw in the play, it is that the second act has Gruach in hiding and thus away from the audience – such is the strength of her portrayal, I felt bereft every time she was off-stage.

Opposite her is a very nuanced and sensitive performance from Jonny Phillips as Siward – leader of the English forces. His struggles to come to terms with his mission and the shifting political and emotional demands placed on his shoulders are central to our emotional engagement with the text.

Credit must also go to Tom Gill – a recent graduate – who makes a very engaging contribution as the Boy Soldier. His journey from youthful exuberance through to a more conflicted and disturbed adulthood is the other main strand to the narrative - his performance marks him out as a young talent to watch.

Roxana Silbert has directed with assurance and clarity of purpose. There is more humour than the premise of the play might suggest and she handles the transitions in tone with great skill. Her ensemble create some wonderful moments that will linger in the mind for many months.

It is always hard to predict whether new plays will be rewarded with revivals and future productions but it is my hope that other companies will explore it – it is worthy of their attention and that of a wide range of audiences.