In London in 1666, the Great Fire happened, turning the city’s streets into a dangerous labyrinth. In the ruins of the burned St. Paul’s Cathedral, a man’s body was found with a fatal wound to the back of the head and his thumbs tied behind his back— it was a sign of regicide. James Marwood, a clerk in the government service, is assigned to track down the avenger. He saves from death a decisive and ungrateful young woman who is ready to do anything to protect her freedom. Cat Lovett, like many others in London, hides her secrets in this difficult time. When a second victim with bound hands is discovered in the dirty waters of Fleet Ditch, Marwood realizes he is on the trail of a killer who will stop at nothing to get revenge.