The mythical Dukedom of Dornoch lies in the heart of the medieval kingdom of Scotia. Behind the walls of an immense castle the Duke of Dornoch and his people are confronted with an early winter, more bitter than any in living memory. At the same time, they are faced with a sudden turn of events that spirals them down into the turmoil of invasion and war with two of their most ancient enemies, England and the dreaded Vikings. Duke Brian must rally his people and protect them and Castle Dornoch, the impregnable fortress that is their succour and their prison during that fearful winter.
When the disappearance of a young prince complicates matters, the castle is rife with rumour and political intrigue. The Duke and his beautiful wife Margaret are at the centre of the maelstrom, their deep love tested by the strains of their country's needs. A story of heroes, villains and ordinary people caught up in the privation of war, The Castle is a suspenseful and sweeping saga of one people's trial and triumph.