There is no more apt time to adapt Pat Barker’s Regeneration trilogy for the stage. The centenary of World War I has not just arrived, but been stoked by countless documentaries; the Tower of London’s ceramic poppies attracted visitors in their thousands. Yet this play still manages to capture something fresh – and raw. Its focus on recovering soldiers makes us question notions of patriotism and heroism all over again.

The show ambitiously covers Barker’s first novel and then takes scenes from the second and third in the series. It follows a group of ‘shell-shocked’ soldiers, recuperating in Craiglockhart, a psychiatric hospital near Edinburgh. Among them are the poet Siegfried Sassoon, who has feigned madness to escape (and published a declaration to announce) the futility and horrors of war. Less willing patients include Bradford boy turned officer, Billy Prior, suffering from mutism, nightmares and survivors’ guilt. Both are treated by the progressive Captain Rivers, a sympathetic psychologist who becomes a surrogate father figure to these men. Nevertheless, his task is to ‘cure’ the soldiers, to get them back out on the field as soon as possible.

The tension builds throughout the first half, with more than one moment where the audience themselves jump in shock. The second half seems stronger, and more powerful. We observe the growing friendship between Sassoon and eager ‘grammar school boy’ poet, Wilfred Owen. A scene in which the two redraft Anthem for Doomed Youth works well, with the audience willing the poets to reach the final, known version. The repressed sexuality of Sassoon, Owen and others runs throughout the piece; Craiglockhart is a male environment, as were the trenches. However, the most troubling scene remains Captain Rivers’ visit to a doctor who practises electroshock treatment. The pain inflicted on traumatised private soldiers is almost unbearable to watch.

Few flashbacks and time shifts are attempted here. This is a faithful, chronological adaptation. The performances are engaging; Stephen Boxer as Captain Rivers, superbly captures the conflicted feeling of the doctor and hints just enough about his own pre-war past. The set is simple; maybe because the patients’ minds and memories are elsewhere, not Craighlockhart. In a packed Tuesday night audience, there were moments when a chuckle rippled from somewhere in the auditorium. Yet there was no universally comic, laugh-out-loud moment. The audience were more often united in horror, respect and admiration.