The theatres are padlocked. Christmas has been cancelled. It is 1657 and the unloved English Republic is eight years old.

Though Cromwell's joyless grip on power appears immovable, many still look to Charles Stuart's dissolute and threadbare court-in-exile, and some are prepared to risk their lives plotting a restoration. For the officers of the Republic, constant vigilance is needed. So, when the bloody corpse of a Royalist spy is discovered on the dung heap of a small Essex village, why is the local magistrate so reluctant to investigate? John Grey, a young lawyer with no clients, finds himself alone in believing that the murdered man deserves justice.

Grey is drawn into a vortex of plot and counter-plot and into the all-encompassing web of intrigue spun by Cromwell's own spy-master, John Thurloe. So when nothing is what is seems, can Grey trust anyone?