That scene is as inevitable as it is conveniently placed, and the weakness of the play is its similar predictabilities. The schematic development requires that the family loses someone on Bloody Sunday, and it's the person who provides bonus points for irony. We would have more to appreciate with here and there if our understanding of more characters developed. For example, Loreen's love interest says more than once that he makes no apologies for being a soldier or for being posted there; after the concluding violence, the implications of that could become clearer than it does: we could feel we understood him for the first time.
The British were the bad guys, historically, in their ostensibly necessary occupation, but care was taken here to not make them two-dimensional ogres (thus the above romance). There were enough police state tactics to not need to exaggerate, as instances of firing on civilians not only went unpunished but led to promotions. So it's not implausible that a charismatic preacher of nonviolence, as Emmett was, would be imprisoned by the British instead of encouraged. This play is a lesson in the bad decision-making of the period.
, Ireland, Roger Williams University, Roger Williams University Theatre, More