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.
The Sins are shocked by Merlin's longtime deception. Meanwhile, Merlin declares that Arthur has been recognized as the King of Chaos.
Merlin rescues Elizabeth, who barely evades a falling boulder on her way to the Demon Realm with Meliodas. The Sins realise the Demon King is alive.
A vicious beast in his true form, Cath attacks the reawakened Arthur. Now separated from the Sins, Merlin attempts to take on the monster herself.
Now that Meliodas is the Demon King, he cannot remain on earth. Though his friends acknowledge his fate, they are unable to accept it.
The long-fought Holy War comes to a dramatic end. Peace returns to the Kingdom of Britannia once again, but a new threat looms on the horizon.
With Escanor's aid, Meliodas and Gowther reach the spirit world, where they aim to split the Demon King and Zeldris back into their own bodies.
Inside Camelot, Arthur makes his last stand against Meliodas and the others. Merlin comes to his rescue, but not before he falls under Cusack's spell.
Escanor converts all of his life energy into magic to defeat the Demon King. Meliodas pleads with his comrade to stop, but Escanor refuses to listen.
Meliodas and Ban intercept a caravan transporting prisoners to the Ten Commandments, but demons still threaten villages in other parts of Britannia.
Elizabeth and Meliodas face the Demon King, who now possesses the body of Zeldris. Meanwhile, the Sins clash with a beast summoned by the Demon King.
Trapped in Melascula's magic, Meliodas breaks the magic at the cost of his emotions. Out of cocoon comes a very different Meliodas who will be confronted by the mightiest of the sin.
Having taken over Margaret's body, Ludociel appears in Liones and declares a holy war against the Demon Clan. Chandler searches for Elizabeth.
Peace returns to the Kingdom of Liones. Although Elizabeth is still under a curse, Meliodas assures her there is a way to break it.
As Meliodas absorbs every last one of the Ten Commandments, Merlin attempts a forbidden spell to stop the birth of a new Demon King.
King and Diane take refuge in the Fairy King's Forest to escape the Ten Commandments. But Gloxinia and Drole find them after a peaceful interlude.
Merlin faces Zeldris, whom Meliodas has ordered to gather the Commandments. Margaret, Hendrickson and Dreyfus continue their search for Gilthunder.
Escaping purgatory, Ban faces the Demon King, who now possesses Meliodas’ body. Elizabeth and the others make their way into the spirit world.
The new Holy War commences as the allied forces of Stigma face off against the Demon Clan. Derieri decides to surrender her Commandment to Zeldris.
Ban searches purgatory for Meliodas. King, Deriri and the others head to Heaven's Theater to rescue Elizabeth, who's been abducted by Estarossa.
Sensing Elizabeth's magic, Derieri appears before the Stigma army. Estarossa follows her, but Sariel and Tarmiel have other plans for him.
Zeldris and the Sins corner the Demon King in both realms, but the King separates from his son's body and possesses Britannia itself as his new vessel.
Meliodas disbands the Deadly Sins and departs with Elizabeth. But his companions aren't going to let him go without a fight, and Hawk holds the key.
Diane destroys the source of the Demon King's magic. Meanwhile, Escanor continues fighting the Demon King at full power, exceeding his limits.
Diane tells Elizabeth that she met someone who looked just like her in the past. Meliodas denies knowing anything about it when Elizabeth asks.
Estarossa professes his love for Elizabeth. When he loses control after absorbing three of the Commandments, Stigma's army faces him in a final battle.