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.
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.
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.
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.
Diane tells Elizabeth that she met someone who looked just like her in the past. Meliodas denies knowing anything about it when Elizabeth asks.