It is the year 1586. England is awash with traitors, plotting to assassinate the Queen and bring about a foreign invasion. The young physician Christoval Alvarez, a refugee from the horrors of the Portuguese Inquisition, is coerced into becoming a code-breaker and agent in Sir Francis Walsingham's secret service. In the race to thwart the plot, who will triumph - the ruthless conspirators or the equally ruthless State?

Oxford, Spring 1353. When young bookseller Nicholas Elyot discovers the body of student William Farringdon floating in the river Cherwell, it looks like a drowning. Soon, however, Nicholas finds evidence of murder. Who could have wanted to kill this promising student? As Nicholas and his scholar friend Jordain try to unravel what lies behind William's death, they learn that he was innocently caught up in a criminal plot.

Matthew Bartholomew, unorthodox but effective physician to Michaelhouse college in medieval Cambridge, is as worried as anyone about the pestilence that is ravaging Europe and seems to be approaching England. But he is distracted by the sudden and inexplicable death of the Master of Michaelhouse - a death the University authorities do not want investigated.

London, 1654. Oliver Cromwell is at the height of his power and has declared himself Lord Protector. Yet he has many enemies at home and abroad. London is a complex web of spies and merchants, priests and soldiers, exiles and assassins. One of the web's most fearsome spiders is Damian Seeker, agent of the Lord Protector. No one knows where Seeker comes from, who his family is, or even his real name. All that is known of him for certain is that he is utterly loyal to Cromwell and that nothing can be long hidden from him.

LONDON, 1590. Queen Elizabeth I's control over her kingdom is wavering. Amidst a tumultuous backdrop of Spanish plotters, Catholic heretics and foreign wars threatening the country's fragile stability, the body of a small boy is found in the City of London, with strange marks that no one can explain. When idealistic physician Nicholas Shelby finds another body displaying the same marks only days later, he becomes convinced that a killer is at work, preying on the weak and destitute of London.