The Wicked Day is the story of Arthur, mythological King of the Britons, and of his bastard son Mordred who is eventually to unseat and kill him. In the story Mordred is abandoned accidentally and raised by the inhabitants of a poor fishing village on the coast. Eventually he is recovered by his mother, Arthur's half-sister Morgause, and plans are put in motion that drive the hapless youth toward his own and his uncle's deaths on the battlefield.