The year is 1570. "A sadistic killer haunts England's streets, sent by a secretive band of plotters known only as The Diamond League. With agents across Europe, their goal is to provoke a bloody, religious war. Jack and Amy Cole - servants and spies - are reluctantly drawn into the service of Queen Elizabeth's spymaster, Francis Walsingham.
Jack is deposited in York, where he is encouraged to betray his fellow Catholics. He infiltrates the Jesuit brotherhood - but can he bring himself to destroy them?
Amy is dispatched to France, to spy on the household of Catherine de Medici. Disguised as a great lady, she is drawn into a glittering, yet perilous, world of intrigue"