One of the great aspects of a drama festival like the Flash is the wide range of subjects and styles that the individual companies might choose to perform. You can find introverted little solo shows that concentrate on one event or one emotion; comedy two-handers that give you an insight into other people’s lives through making your sides split; domestic dramas; questions of ethics; or something like The Cost of Freedom, which explores the monumental tragedy of the lives (and indeed, deaths) of those caught up in the slave trade, still rife in America little more than 150 years ago.

In this play we meet a group of six people – two sisters, two men taken forcibly from the families, and a boy accompanied by an older relative (not his father, as he is at pains to point out). Try as they might to flee from capture, they are taken and threatened by unnamed white men, armed with rifles and shotguns, one of whom we see, the rest are left to our imagination. But the slaves escape from their imprisonment, and whilst on the run we get to know them a little more; their childhood memories, their hopes, their previous work and family lives, and how they got into this perilous state. When one of the men is re-captured, he is threatened with death unless he leads his captors to the other five escapees. Will he save himself, or will he save them? You’ll have to see the play to find out.

By means of a combination of athletic, physical theatre, unsettling darkness, emotional spiritual music and sheer fantastic acting, this ensemble have devised a haunting, terrifying, shocking recreation of the kind of horror that those poor people would have experienced in the United States during the slave trade. We feel their physical pain – and see the scars. We hear their pleas for mercy – and how they are abused. We long for them to gain their freedom – and are distressed that it doesn’t happen. I feel no disgrace that the events and performances in this play reduced me to tears. This is the kind of production that hits you immediately in all your senses but then gets even better and better the more you think about it.

Each member of this superbly gifted cast endows their role with an incredible sense of humanity and vivid characterisation. D’angelo Mitchell’s Cato, for example, is studiously cynical, trying to control the others where possible, bitterly alone and without hope of ever seeing his family again. Mr Mitchell gives us a really strong performance that taunts your emotions and reveals so much about the nature of loyalty. Sisters Jo and Jess, played by Sarah Awojobi and Lyric Impraim, have each other’s company for support, keeping themselves to themselves, trying not to be noticed for fear of abuse. Ms Awojobi’s frightened tears and Ms Impraim’s protective stare will stay with me a long time.

Kieran James’ young Zeke, attempting to make sense of what has become of his life, and so vulnerable without his parents, is a brilliant portrayal of someone who has seen too much too young, and Mr James’ clumsy but heart-warming attempt to chat up the girls was one of the highlights – he is on terrific form in this play. Zeke is desperately attached to Michael Gukas’ Noah, a man who remains assertive in the face of his oppressor, and whose priority is to take care of the boy and try to guide them all into freedom. As always, Mr Gukas gives a sensational performance, combining softness and strength in his amazingly expressive voice and physical presence; he’s surely destined for Great Things.

And there’s Nafetalai Tuifua’s Nigel, the sensitive, artistic man who cannot come to terms with his change of status after playing violin for his master, now facing a fight for survival at all costs. Mr Tuifua is always a joy to watch; you cannot help but smile with his happiness and cry with his agony, and, particularly during the musical scene, he is a sublime Mr Entertainer. And a word of congratulation for the unnamed oppressor, who maintained his threatening air of cruelty throughout, even from off-stage. From my front row seat I felt completely wrapped up in every confrontation, tragedy, and indeed occasional moment of humour that befell them all.

Everything about this production is impressive; not only the sheer emotion of the plot and atmosphere, but the athletic, almost balletic, physical movement of the cast, their ability to draw you in to their tale, the technical consistency and authenticity of their accents, the musicality of their spiritual, even the choice of their once smart, now ragged, clothing. This production should surely have a life after Flash – I’m sure it would be perfect for Edinburgh – and it’s a play that everyone should see in these divided times we’re facing. Superb stuff!