DS Kate Fleming

Kate Fleming is a detective constable with a gift for undercover work, sent by anti-corruption unit AC-12 to embed herself in a high-flying police team and quietly investigate its star officer. She is sharp, disciplined, and quietly ambitious, balancing the strain of a double life with the pull of a young son waiting at home.

McClure plays watchfulness as a skill rather than a mood — you see Kate calculating every room she walks into, weighing loyalty against evidence. The show trusts her competence without softening it into likability, and that friction, a good cop who has to lie constantly to do good, makes her the moral gauge the whole series checks itself against.