Det. Sgt. Maureen Connell

Maureen Connell is a detective sergeant working inside the unit that investigates police corruption, a job that makes her unpopular with the very colleagues she used to call friends. Sharp, watchful and Scottish-blunt, she does the work without apology, weighing loyalty against evidence in a world built on both.

The show trusts her to be competent rather than decorative, and Siobhan Redmond plays that competence with a dry, unshowy steadiness that never begs for sympathy. What sticks is how ordinary her professionalism looks next to the moral rot around her — she simply keeps doing the job properly, which turns out to be the hardest thing anyone in the series attempts.