"The Seven Deadly Sins: Cursed By Light" serves as a sequel to the original series, continuing the adventures of the titular group of knights in the kingdom of Britannia. The story begins after the defeat of the Demon King, with peace seemingly restored. However, the emergence of a new threat disrupts this tranquility. The Supreme Deity, mother of Elizabeth and ruler of the Goddess Clan, seeks to impose her own order on the world, viewing the coexistence of humans, demons, goddesses, and other races as a flaw that must be corrected.

Meliodas, the leader of the Seven Deadly Sins, and Elizabeth, his beloved, find themselves at the center of this conflict. Despite their efforts to live a peaceful life, they are drawn back into battle as the Supreme Deity's plans unfold. The Supreme Deity aims to use the power of the Sacred Tree, a mystical entity tied to the fate of the world, to cleanse the land of all races except the goddesses. This plan threatens not only the fragile peace but also the lives of countless beings.

The Seven Deadly Sins, alongside their allies, must confront this new adversary. The group includes Meliodas, the Dragon's Sin of Wrath; Ban, the Fox's Sin of Greed; King, the Grizzly's Sin of Sloth; Diane, the Serpent's Sin of Envy; Gowther, the Goat's Sin of Lust; Merlin, the Boar's Sin of Gluttony; and Escanor, the Lion's Sin of Pride. Each member brings their unique abilities and resolve to the fight, united by their shared goal of protecting Britannia and its inhabitants.

As the story progresses, the group faces numerous challenges, including battles against powerful enemies and the revelation of deeper truths about the Sacred Tree and its connection to the world's balance. The narrative explores themes of sacrifice, loyalty, and the consequences of wielding immense power. The characters' relationships are tested, particularly the bond between Meliodas and Elizabeth, whose love has endured across lifetimes.

The climax of the story involves a decisive confrontation with the Supreme Deity and her forces. The Seven Deadly Sins and their allies must harness their full strength and work together to prevent the destruction of their world. The resolution of the conflict brings closure to the overarching narrative while leaving room for the characters to move forward in their lives.

Throughout the series, the interplay between action, character development, and world-building remains central. The story builds upon the established lore of the "Seven Deadly Sins" universe, expanding on the roles of the Goddess Clan, the Sacred Tree, and the intricate relationships between the races. The narrative maintains a balance between high-stakes battles and moments of emotional depth, ensuring a cohesive and engaging experience for viewers familiar with the franchise.