When a kingdom falls into the hands of tyrants, the deposed princess sets out on a quest to find a group of ancient evil knights to help her take back the kingdom.
As peace returns to the Kingdom of Liones, the Sins decide to pursue separate paths to continue their own individual journeys. Gowther brainwashes Guila into falling in love with him, while Diane spends time as a normal human thanks to Merlin’s Minimum Tablets, which allow her to shrink in size. Diane also slowly regains her past memories, which include her prior encounters with King, and reunites with Matrona, her mother figure, and the giant race. Meanwhile, Ban departs for the Fairy King’s Forest with King and the Holy Knight Jericho to continue his duties as he is revealed to be the current Fairy King. Back in Liones, King Bartra’s Vision ability shows him an omen of the impending dangerous Holy War that lies ahead in Camelot.
Elizabeth Liones' search for the Seven Deadly Sins started ten years after their rumored coup d'état. While villagers thought of it to be a myth, Elizabeth came to search for them anyway in order to rescue the king (her father) and the rest of the royal family who were imprisoned by the Holy Knights.
In the village, a young boy named Peliodas who aspires to be the Dragon's Sin of Wrath (Meliodas) attempts to fight the demons to stop his community from continually capturing sacrifices for them, but fails. They are ultimately saved by Ban and Meliodas, along with Gowther, Escanor, Merlin and Elizabeth.
An alliance is formed between the Arc Angels and the forces of Liones to put an end to the war. Ban ventures into the depths of Purgatory to find Meliodas's emotions and bring them back.