The City and the City (2018)

Two cities share the same streets in this four-part BBC Two adaptation of China Miéville's novel, and their citizens are trained to unsee each other, because crossing without permission brings down a shadowy power called Breach. David Morrissey's detective is handed the case of a student found dead in one city with ties to the other, and a society organised around not looking turns out to be the silo's banned relics taken to their logical end.