"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 spy in Sir Francis Walsingham’s espionage service. In the race to thwart the plot, who will triumph – the ruthless conspirators or the equally ruthless State?"