Based on China Mieville's novel of the same name and written by the acclaimed Tony Grisoni, this four-part series follows the life of Extreme Crime Squad Inspector Tyador Borlú as he investigates the murder and mutilation of a foreign student. Played by David Morrissey, Inspector Borlú is thrown into a political battle when evidence reveals that the victim was involved in the political turmoil of his city, Besźel, and its twin city, Ul Qoma. Due to the citizens of each city being forbade to see each other, Borlú embarks on a dangerous journey from one reality to another.