When the RSC does modern drama it usually lays on an ultra-worthy yarn with a huge cast, dozens of fancy costumes and a three-hour running time. Miraculously, its new co-production with the Arcola avoids these faults and delivers a terse, gripping 75-minute documentary drama based on the prison diary of Turkish journalist, Can Dundar. In 2015 Dundar received proof that his country’s intelligence service was attempting to supply arms to Syrian rebels. He knew that if he released the material he might face jail but he published it anyway and was threatened with life imprisonment. Peter Hamilton Dyer, well known for impersonating journalists, plays Dundar as a loveably cerebral type determined to stick to his principles.

The spare and ingenious set, by Charlie Cridlan, consists of three white oblong tables that can be aligned to imitate any location the story requires: a cell, a bed, an editor’s office, a dinner table, an exercise  yard or an interrogation suite. Quizzed by a prison officer, Dundar is asked if he’s a criminal or a terrorist. ‘Criminal,’ he replies, ironically accepting the officer’s assumption that to be literate is to be an outlaw. ‘Who introduced you to crime?’ ‘My mother,’ he says. Does he intend to reform? No, he will carry on offending for the rest of his life.

The show evolves into a meditation on jail, its privations and consolations. Dundar is sustained during periods of despair by erotic reveries about his wife’s dancing skills. His stark white cell inspires a deep spiritual craving for colour. Out in the exercise yard he raises his eyes and drinks in the sky’s blueness. The walls of the jail turn out to be porous. Supporters throw gifts of fruit into the yard which he crushes to extract their pigmented juice. And he manages to get hold of a newspaper where he reads of the international outcry that greeted his detention. It becomes clear that the Turkish authorities are not yet adept in the usages of repression and Dundar’s life sentence is reduced to a matter of months. But he still finds himself in legal difficulties and in the final moments a gunman takes a pot shot at him outside a courtroom.

This is a riveting and beautifully staged analysis of totalitarian paranoia and its clumsy attempts to curtail free expression. There is one false note. At the end, taped speeches by Owen Jones and Jess Phillips MP are played to the departing crowd as if to suggest that Britain is a Turkey-in-waiting and that left-wingers here might soon face jail time for speaking their minds.

Touching the Void is a book, a movie and now a stage show. The tale dates from 1985 when two ambitious British climbers attempted the west face of Siula Grande in the Peruvian Andes. Joe slipped, Simon cut the rope and scrambled to safety leaving his pal dangling in a crevasse with a broken leg. Joe’s ordeal lies at the heart of the story whose focus is slightly blurred by the presence of a third character, Richard, who stayed at base camp keeping an eye on the adventurers’ gear.

But the adaptor, David Greig, has chosen to introduce a fourth figure, Joe’s sister Sarah, and to make her the central character. This has one advantage. Sarah’s ignorance of mountaineering allows non-Alpinists like me to learn its jargon. ‘The void’ means the intoxicating fear of death that compels climbers to pursue their hobby. ‘The hill’ is a generic name for any peak they attempt to surmount. ‘A bivvy’ is an overnight camp. The descent, known as ‘downclimbing’, accounts for four times more accidents than its converse.

Having completed her tutorial, Sarah travels to Peru and meets Richard who relates the details of the climb to her. But neither figure was present on the mountain so their talk feels like a distraction from the key drama. Joe and Simon set off up the slope which is represented on stage by a double-pyramid of triangulated spindles covered in tracing paper. They scale this unsteady structure by creeping along the spindles and kicking holes in the paper to gain footholds. Each step causes the summit to wobble fearfully. At times the entire Andes seem about to topple sideways like an ill-constructed IKEA sideboard. A symbolic representation might have worked better. After Joe plummets into the icy vaults, Sarah appears beside him having assumed the character of Agony or Defeat. She thrashes his broken leg with a pole while he whimpers uncontrollably on stage.

The West End has seen more uplifting passages of theatre. The script is amplified with John Martyn songs and other feelgood effects but it never comes close to the emotional intensity and visual splendour of the movie. Final note: my 13-year-old son loved the show enormously and threatened dire retribution if I said a word against it.