Reunited with Lancelot for the first time since their tragic accident, Tristan must learn to conquer his inner demons in order to save his mother's life.

14 years since the Kingdom of Liones defeated the Demon Clan and brought peace to the land, Prince Tristan is tormented by his inability to control two great powers: the Demon Clan power of his father, Meliodas, who served as captain of the Seven Deadly Sins as the Dragon Sin of Wrath, and the Goddess Clan power of his mother, Elizabeth. When Elizabeth's life is threatened, Tristan flees the kingdom and heads toward Edinburgh, where Deathpierce who was once a member of a group of the kingdom's Holy Knights, the Pleiades of the Azure Sky maintains his castle. But what are Deathpierce's intentions?