Theatre reviews: The Factory | The Tailor of Inverness

THE Second World War cost 45 million lives worldwide; and when it finally ended, many of those who had lived through it could hardly believe that they – and the world – had somehow survived in recognisable form. Badac's new show The Factory takes us straight into the heart of that darkness, onto the very borderline of death and survival as it was experienced by the millions of Jews, gypsies, homosexuals and political dissidents sent into the horror of the Nazi death camps.

For an unforgettable 50 minutes, in the dank layers of cellars beneath the Pleasance, we, the audience, become fellow prisoners, shouted at, harangued, told to line up and move on right into the final gas chamber itself, alongside the three trembling, terrified, and eventually naked companions who are the members of the cast. It is a horrific experience, driven home by a script of simple repeated strands of shouted dialogue – "tell me what they will do to us", "if we do nothing they will kill us" – that land like hammer blows in the brain.

Something tells me that those who already care about man's inhumanity to man will be deeply moved and affected by this piece, whereas those who care more about the dust on their designer T-shirts will simply be irritated; and there is sometimes a sense of a young company gaining credit for artistic seriousness by simply choosing a subject of unparalleled horror, and turning up the volume. But there is some subtlety here, too, in the relationship between prisoners and those chosen from among them to be their guards; and the moment when we say that this story no longer needs to be retold will be a moment of immense danger, for a civilisation that once said "never again", and meant it.

The father of the Scottish writer and actor Matthew Zajac was another survivor of the war, a Polish tailor who somehow found himself, in the late 1940s, living and working in the "cool air of Inverness". The Tailor Of Inverness is Zajac's solo account of his own long journey towards the truth of his father's wartime story, as Mateusz Zajac survived, and sometimes complied with, both Nazi and Soviet occupation to find himself eventually into the allied forces. Zajac's script is not perfect; sometimes it becomes too much of an unprocessed history lesson, and it loses shape and structure in the middle.

But in Ben Harrison's graceful production, the telling of the tale is both strongly theatrical and visually compelling, with subtle use of light and sound, video and still images, and the wonderful live fiddle music of Gavin Marwick. And the show's painful journey towards the truth fits irresistibly with this year's festival theme of Artists Without Borders; as Zajac searches for the essence of his father not only along the shifting border between Poland and Ukraine, but also in the more subtle and disturbing borderlands between Nazis and allies, friends and enemies, good men and bad.

• The Factory, until 24 August. Today 4:30pm.

• The Tailor of Inverness, until 25 August. Today 2:55pm.