Cat and Mouse (S09E08)

Title: Cat and Mouse Plot: The team confronts their most daunting obstacle yet: locating Lucas North, their Section Chief, friend, and one of MI5's finest agents. Concerned about their emotional attachment, Harry opts to enlist a specialist to assist in the pursuit. However, tracking down a man with nothing to lose proves to be a formidable task. As the urgency of the search escalates, both Harry and Lucas find themselves ensnared in a perilous game of cat and mouse, where the stakes have never been higher.