Borderline follows DCI Philip Boyd and DI Aoife Regan through the border region between Northern Ireland and Ireland. Eoin Macken plays Boyd, a devout Protestant; Amy De Bhrún plays Regan, an atheist. They could hardly be more different, but the discovery of a young woman's body requires them to work together. Personal differences and political tensions complicate the partnership.
Character development is central. Boyd and Regan have to overcome their differences and learn to operate as a team. Their exchanges combine friction with occasional humor, making the relationship involving and credible.
The direction contributes considerably to the atmosphere. The camera captures the rugged beauty of the Irish landscape while reinforcing the darker mood of the investigations. Ray Harman's music complements the images and adds emotional force to the scenes.
The performances are convincing. Macken expresses Boyd's internal divisions, while De Bhrún gives Regan determination and vulnerability. Supporting characters add further depth to the cases and the world around the investigators.
Beyond its crimes, Borderline considers the political and social tensions between the two jurisdictions. Cooperation between police forces is not simply an administrative detail. The series uses those difficulties, and the implications of Brexit for cross-border crime, to give its procedural framework additional substance.
Borderline offers an involving combination of crime drama, character work and political themes. Strong central figures, an engaging story and a convincing sense of place make it worth watching for viewers who want more than a case to solve.