The 306: Dusk is the final instalment of Oliver Emmanuel’s extraordinary 306 Trilogy: a thoughtful, compassionate and moving series of plays dealing with the ramifications of the First World War, exemplified by the 306 British soldiers executed for mutiny, cowardice or desertion by their own government. Unfortunately, this final chapter is the least successful of the three.

The 306: Dawn and The 306: Day dealt with, respectively, soldiers in the trenches, and their womenfolk back home. The 306: Dusk attempts to link these stories to the present day by drawing parallels between soldiers’ experiences in the fields of France and Iraq, and their resultant Shellshock / Post Traumatic Stress. These events, separated by a century, are described by Louis, a young volunteer in the Yorkshire Regiment, and Keith, an alcoholic haunted by the violent death of an Iraqi civilian. Their stories are linked by Rachel, pregnant granddaughter of a WW1 Tommy, who oversees tourist trips to the Somme battlefield. The stage set is a stepped garden that doubles as a trench, ad whose soil occasionally yields disturbing secrets. Musicians (including a choir) are faintly visible behind a gauze on which trees are projected.

Sadly The 306: Dusk fails to maintain consistency with it’s predecessors. Both The 306: Dawn and The 306: Day were staged in unusual locations (Dawn in a farmer’s barn, Day in the old ballroom of Perth’s Railway Hotel). Perhaps it is right that Dusk was performed in Perth’s recently reopened theatre, but the limitations of a traditional theatre space prevent the immersive experience so successfully deployed in the first two plays. In the previous productions the performers moved amongst the audience, but the third does not attempt this, resulting in a distancing effect that is magnified by the script. The characters in Dusk deliver their stories in the third person so, regardless of the time period we are watching, events have already happened and the drama comes to us second hand. This makes for a series of extended monologues rather than actors playing against each other, as they had done so intensely in the other two. The energy that this gave scenes in the first two plays is lost in the third, replaced by somewhat overwrought storytelling. Several times, the character of Keith (who’s adherence to protocol in Iraq resulted in him killing a child) shouts “I did the right thing!” but it lacks the intended ironic impact. Had the incident itself been dramatised we would have felt the same pressure and understood his split second decision to fire his gun. Instead he tells us about the killing three years later, in alcoholic self-pity. Emmanuel’s decision to have all the characters Tell rather than Show weakens the entire play.

Despite the disappointments of Dusk it has some striking moments, mainly thanks to the music (composed by Gareth Williams) which once again brilliantly combines story and emotion (one song lyric consists solely of the names of Glasgow streets. We learn that the Scottish soldiers of the Somme gave the same names to their trenches). The play is rescued, twenty minutes from the end, when the young Tommy is executed for desertion (this moment is performed rather than told) and the timelines are suddenly pulled together. The gauze backdrop is lifted and the musicians and choir join the cast to sing the names of all 306 executed soldiers. It’s a moment that matches the emotional heights of the first two plays, and proves a fitting finale to the play and the whole trilogy.

Despite my misgivings about this final instalment, there is no denying Emmanuel’s 306 Trilogy is an remarkable achievement and a fitting tribute to those who die, or who return permanently damaged, protecting the freedoms that we enjoy.

The 306: Dusk runs in Perth’s Theatre until Saturday 27th October.