London, September 1666: The Great Fire rages through the city, even the impregnable cathedral of St. Paul's is reduced to ruins. Among the crowds watching its destruction is James Marwood, the son of a disgraced printer and reluctant government informer. A semi-mummified body is discovered in the ashes of St. Paul's, in a tomb that should have been empty. Under orders from the government, Marwood is tasked with hunting down the killer; the investigation leading into treacherous waters...