I wanted to give this play a few days to settle in my mind before putting “virtual pen to paper”. When I was deciding which shows we wanted to see at the Edinburgh fringe, a top priority was for them to be challenging, experimental, daring performances that we’d be unlikely to see nearer to home. A play where seven naked Soviet soldiers are chucked in a cellar by the Nazis and left to die, and who therefore resort to cannibalism in order for some of them to survive, sounded like it ticked all those boxes.

At first the nudity feels quite shocking and bizarre – it’s just something you don’t often see on a stage right from the start of a play. Normally stage nudity would happen in combination with a sense of comedy or eroticism. But this is just a depiction of man at his most raw, basic and defenceless. The shock quickly changes to acceptance as an almost natural form of existence, which in turn soon grows into empathy as you imagine how you would react under the same circumstances. Being soldiers, they’re automatically programmed to respond to rank, and amongst those seven soldiers you’ve got a Captain, a Senior Lieutenant, a Lieutenant, and a Junior Lieutenant, as well as three Privates. But without the outward show of uniform, that sense of rank is removed. Each individual man’s natural tendency to lead, or to obey, takes a more prominent role in how that person copes with their relationships. With this set of men, it quickly leads to power struggle, as the Captain’s superiority is questioned by his more ruthless and ambitious “alpha male” subordinate.

I wasn’t aware, until I read the programme notes, that cannibalism was not uncommon in the Soviet Union during the war, when forced starvation was employed as an active policy by Stalin and Hitler. For the guys abandoned in the cellar, it becomes a mix of “survival of the fittest” and “noblesse oblige”, as they come to the grisly conclusion that it’s the only way to prolong (some of) their lives in the hope of being somehow rescued. As time inexorably passes by – a projection screen keeps us updated as the days turn into weeks – authority, friendship and loyalty are all tried and stretched to beyond breaking point, and, through natural means and foul, the numbers dwindle.

It’s a stunning, memorable play on so many levels. Not only does it take such serious and challenging subject matter and tackle it head on, it also includes the black humour that you would guess would be an inevitable and vital part of surviving such an experience. There’s quite a lot of scene-setting at the beginning which involves them rattling through the long names of various Russian military officers, which actually feels even more disorienting than the sight of seven naked men. You worry slightly that you’re not going to keep up with what’s happening. But actually that sense of confusion is in perfect keeping with the situation in which the men find themselves. Once the initial confusion has passed, the plot concentrates on the relationships between the soldiers, examining the friendships, the enmities, the levels of independence and reliance, the kindness, the cruelty, the selflessness and the selfishness. All human life is there. People are not always what they seem to be; others have the potential to do things you would never imagine possible.

Structurally, the play has several scenes, each depicting yet another day (or longer) in this hell-hole. Strength progressively deteriorates as they slowly weaken through hunger and lack of exercise. You get a sense of classical drama as the whole story takes place in the same location and has only one theme throughout. Once they cross the Rubicon into cannibalism, there is a symbolic libation scene where they immerse themselves in the blood of their departed comrade. They have blood on their hands – and bodies – for ever after. There is no turning back.

The play specifically examines the nature of deprivation and its effects. The men are deprived of everything – clothing, food, freedom, communication, warmth, family/friends/comrades, information, and hope. Without giving away the full plot, there is a huge sense of irony at the end of the play as you wonder whether those who made the supreme sacrifice did it for nothing. Overall, it’s a fairly negative take on survival, but as the story makes its way to its final conclusion there are some incredibly positive and generous exchanges that give you great confidence in the human spirit.

It goes without saying that the cast are fantastically brave, performing this intense work naked throughout, including lots of physical contact, apparently covered with grime and blood, portraying people in the depths of despair. There’s no hiding place on that stage, no discreet corners or angles where they can take cover, no series of entrances and exits to give the actors a temporary relief from their characters. Whilst these soldiers are alive, they’re on stage. Individually they all give superb performances. Rupert Elmes’ Captain Nikolov gives us a great portrayal of a decent man crumbling under pressure. Walking wounded from the start, he optimistically tries to keep the men motivated and positive, but rapidly falls into self-doubt, and struggles to retain his position. Harvey Robinson’s Ehrenberg is the quiet, natural leader, the kind of man you can rely on in a crisis; balanced and practical, inspiring friendship and confidence, and selfless to the end. It’s an amazingly convincing performance – you hang on his every word. As Lieutenant Kozlov, Marlon Solomon conveys perfectly a level of pessimistic cynicism, whilst still hanging on to his memories and holding out for a positive ending. When the truth behind his character is revealed it’s an exquisite shock, and Mr Solomon absolutely nails both the cynic and the wretch in his performance.

Will Bowden’s Drossov is a powerful ogre of a man, a good soldier to have in your company but with a character so untrustworthy and vicious. You know the kind of man who tries to rule by violence – Mr Bowden inhabits that man in a terrifyingly effective way. John Hoye’s intelligent performance brings out the good, traditional Soviet in Private Sukeruk, a man of strength and experience, no nonsense, naturally dominating, but essentially frustrated at his lack of authority. Matt Houston’s Private Poleko, the Georgian who plays the clown as long as he can until he can take the façade no further, is a great study of a strong spirit that fights so hard to keep on top but whose lack of worldly experience lets him down. It’s an amazing performance. He also embodies the pinnacle of kindness and caring as he protects the simple Private Yuri Yegerov, recruited for his physical strength rather than his mental capacity, played with heart-breaking honesty by Thomas Holloway. For three of these actors, unbelievably, it’s their professional debuts – yet they give us performances of such power and insight, you would think they had years of experience.

This is not an easy watch. Performed at midday during the Edinburgh fringe, an hour and a half later you certainly don’t feel like lunch. But that timing ensures you watch the play with your fullest attention, which it absolutely deserves. It may make you feel sick. It may make you cry. It will certainly make you feel differently about the barbarism of war and the nature of survival. If you can handle the content, this is an extraordinary fulfilling and rewarding play. And you’ll be in awe of the unforgettable performances.