@ Discover 21, Edinburgh, until Fri 6 Mar (and touring schools)

The generations-old social scourge of sectarianism and the modern blight of internet trolling are the toxic combination at the heart of this short, questioning piece by local playwright Jennifer Adam and director Amy Gilmartin, which premiered at last year’s Just Festival. Rather than moralising, it merely invites the viewer to observe what happens when a bullied teenager, Evan (Euan Brockie), finally cracks and lashes out at his Celtic-loving tormentor online.

With none but the most minimal of props, a trio of actors – playing son, mother and father – deliver the piece mainly in monologue, sometimes in heightened prose, sometimes in much earthier language. Somewhat awkwardly and unnecessarily, given that most of the play is performed from seats at one end, a traverse stage has been used.

Brockie dominates the piece, the twitchy, pent-up frustration visible on his face from the get-go. His fellow actors simply have to not drop the ball. In particular, there’s little for Deborah Whyte to get to grips with in her role, a worried mother from central casting, while father (John Love) is a likeable sort who, plausibly for the plot but unusually for the social setting, is a minor celebrity actor. There’s echoes of a young Ewan MacGregor in Brockie’s delivery – honeyed tones soured with malevolent intent. Evan is a warrior in the online gaming world and, metaphorically, in his own life, and when Brockie spits his incriminating outburst it is with frightening, explosive intensity.

In the end, Warrior poses questions rather than giving answers. What is free speech? How do we police the internet? What do words mean? For the traditional theatre audience, it might have been interesting for the play to take more of a stance, but not surprisingly Warrior is touring schools, where it is the jumping-off point for a wider discussion on these exact points, led by the Scottish charity Nil By Mouth. With that in mind, there is much to admire about tonight’s show, an interesting little exploration of a key issue of our time.