1978: The National Front is gaining ground in Hackney. To counter their influence, anti-fascist groups launch the Carnival Against Racism in Victoria Park. Observing the event is Detective Constable Patrick Noble, charged with investigating racist attacks in the area and running Spycops in both far-right and left wing groups. As Noble's superiors are drawn further into political meddling, he's inveigled into a plot against the embattled Labour government as the Winter of Discontent begins to bite.

1983: Under a disciplinary cloud after a Spycops op ended in tragedy, Noble is offered a reprieve by an old mentor. He is dispatched in the early hours to Stoke Newington police station, where a young black man has died in suspicious circumstances. This is Thatcher's Britain now, a new world that Noble unwittingly helped to usher in, where racial tensions are weaponised by those in power. His investigation will expose the dark heart of a nation at war with itself.