In a world where injustice prevails, the Holy Knights of Britannia protect their homeland with their unparalleled magic and strength. Their most sought-after targets are "The Seven Deadly Sins": a group of criminals once regarded as the strongest of Britannia's Holy Knights. Their supposed conspiracy to overthrow the Kingdom of Liones led to their defeat at the hands of the Holy Knights, but rumors persist that the seven infamous knights still live.

Ten years later, the Holy Knights ironically stage a coup d'état themselves and capture the King of Liones, installing themselves as the new rulers of the kingdom. Elizabeth Liones, the third princess of the kingdom, sets out on a journey to find the Seven Deadly Sins and request their aid when she stumbles upon a bar owned by Meliodas, the Dragon's Sin of Wrath and the former leader of the disgraced knights. The pair sets out to find Meliodas' old comrades, but will it be hope or despair that awaits them in their travels?