Cal is a novel that deals with one of the most difficult times in Irish history. It is set against the backdrop of violence and murder that occurred because of the political differences between Catholics and Protestants who wanted very different things for the future of Northern Ireland. Catholics wanted Northern Ireland to merge with Southern Ireland, and become a country independent of Great Britain. Protestants wanted to remain part of Britain. The republican IRA movement used violence, particularly mass bombings that killed thousands of innocent people, to try to get their way, with Protestant loyalist forces retaliating by punishing those who had been a part of the terrorist activities.
On the face of it, this is a complicated novel. The protagonist is a terrorist and a murderer, yet the author asks the reader to see him as a sympathetic character and a victim of his circumstances. Although the novel is presented from Cal's point of view, it is impossible to put aside the fact that he is part of an organization whose modus operandi is to kill innocent people, and who has himself murdered a family man purely because he was a Protestant.
The novel explores many themes but the key themes are politics and religion, particularly the hatred between Protestant and Catholic residents of Northern Ireland. It was adapted as a movie in 1983, starring Helen Mirren and John Lynch.