In London in 1663, rebellion is in the air. Thomas Chaloner, spy for the King's intelligence service, has just returned from thwarting a planned revolt in Dublin, but he soon realizes that England's capital is no haven of peace. Ordered to investigate the shooting of a beggar during a royal procession, he soon learns that the man is not a vagrant, but someone with links to the powerful Company of Barber-Surgeons. Meanwhile, Chaloner's master, the Earl of Clarendon, is locked in a deadly feud with the Earl of Bristol, and an innocent man is about to be hanged in Newgate. In a desperate race against time, Chaloner must find a way to protect Clarendon, track down a murderer, and save an innocent man from the executioner's noose.