1606. England stands divided in the wake of the failed Gunpowder Plot. As a devastating tidal wave sweeps the Bristol Channel, rumours of new treachery reach the King.

In Newgate prison, Daniel Pursglove receives an unexpected - and dangerous - offer. Charles FitzAlan, close confidant of King James, will grant his freedom - if Daniel can infiltrate the underground Catholic network in Bristol and unmask the one conspirator still at large. Where better to hide a traitor than in the chaos of a drowned city? Daniel goes to Bristol to investigate, but soon finds himself at the heart of a dark Jesuit conspiracy - and in pursuit of a killer.