January, 1721. London is reeling from the effects of the greatest financial scandal of the age - the collapse of the South Sea Bubble. William Spandrel, a penniless mapmaker, is offered a discharge of his debts by Sir Theodore Janssen, a director of the South Sea Company, on one condition: he must secretly convey an important package to Amsterdam.

The package safely delivered, Spandrel barely survives an attempt on his life, only to discover the recipient has been murdered, and Spandrel is the prime suspect. Spandrel quickly realises that he has become a pawn in several people's games - British Government agents, and others, are on his trail, believing that the mysterious package contains secrets that could spark a revolution in England.

Spandrel's only chance of survival is to recover the package and place its contents in the right hands. But what are the contents and whose exactly are the right hands?