The setting is England and Ireland in the Dark Ages (historiography), after the fall of the Roman Empire. Mark of Cornwall of Cornwall plans to unify the people of Britain – Celts, Angles, Saxons, and Jutes – under himself as high king to resist Ireland domination. The Irish king, Donnchadh, discovers this and sends troops to attack a Tantallon Castle where a treaty between the British tribes is being discussed. The raid claims the lives of the castle's lord and his wife, but Marke manages to save their young son, Tristan, at the cost of losing a hand. Feeling compassion for the boy, whose father loyally supported him, Marke welcomes Tristan into his home and regards him as a son.