Dorian Kenelm, a young marshland guide known fondly as 'the river king', traverses the Great Mire at the behest of his powerful father; Helen Carmine, daughter to Selannon's sole lord and heir to the Carmine estate, struggles to reconcile the future with her duties to her town; and Christos Nelson, a humble baker's son, lives his life unremarkably but for his dreams of a boundless world beyond the mire.

Meanwhile, across the Evangelium, a lowly scholar is tasked with investigating terrible rumours that may bring the legendary Carmarilla of Scholars to its knees.

Slowly, the eyes of the world are turning towards the lonely marshland village of Seton. The river of time churns ceaselessly, bringing with it the sediment of the mountains and the dirt of a history that should never have been forgotten.