London, 1593. Five years on from the Armada and Elizabeth's England seems secure. But there is always a plot afoot. Robert Cecil, the Queen's spymaster, needs Nicholas Shelby -- reluctant spy and maverick physician -- to embark on an undercover mission once again. One that he can't refuse, if he wants to keep Bianca Merton safe. Crossing the seas to Marrakesh in search of a missing informer, Nicholas hunts the dingy back alleys and dazzling palaces for the truth. But his search reveals a deadly conspiracy, one far more difficult to survive than he'd ever imagined. And back in London the plague has returned, ravaging the streets and threatening everything he holds most dear.