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.

When a boy leaps to his death from a bridge in the northern town of Umeå, Sweden, police discover drugs scattered in the snow near his body. The town has seen a dramatic increase in narcotic use among its youth, but nobody knows where the pills are coming from.

London, September 1666. The Great Fire rages through the city, consuming everything in its path. Even the impregnable cathedral of St. Paul's is engulfed in flames and reduced to ruins. Among the crowds watching its destruction is James Marwood, son of a disgraced printer and reluctant government informer. In the aftermath of the fire, a semi-mummified body is discovered in the ashes of St. Paul's, in a tomb that should have been empty. The man's body has been mutilated, and his thumbs have been tied behind his back.

England, 1176. Aelred Barling, esteemed clerk to the justices of King Henry II, is dispatched from the royal court with his young assistant, Hugo Stanton, to investigate a brutal murder in a village outside York. The case appears straightforward. A suspect is under lock and key in the local prison, and the angry villagers are demanding swift justice. But when more bodies are discovered, certainty turns to doubt - and amid the chaos it becomes clear that nobody is above suspicion.

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.