The Seven Deadly Sins embark on a search for the fabled "sky fish" which leads them to a far-off land where Meliodas and Hawk chance upon an enchanting dwelling gliding high above the clouds inhabited entirely by winged beings. Meliodas, however, is not granted a warm reception – accused of a crime, he is promptly incarcerated. In the meantime, the natives are primed for an elaborate ceremony designed to shield them from a hideous monster that only awakens once every 3,000 years. Nevertheless, chaos ensues when the Six Knights of Black, a troop of demons, make an appearance and unleash the fearful beast to wreak havoc on the Sky Palace's citizens. Amidst a thrilling struggle, Meliodas and his allies rise to take on the challenge posed by the Six Knights of Black.