"The Seven Deadly Sins: Four Knights of the Apocalypse" is a sequel to the original "The Seven Deadly Sins" series, set in the same universe but focusing on a new generation of characters. The story centers on Percival, a young boy raised in isolation on God's Finger, a remote and peaceful island. Percival's life takes a dramatic turn when his grandfather, Varghese, is attacked by a mysterious knight named Ironside, who claims to be Percival's father. Varghese reveals the truth about Percival's origins and entrusts him with a mission to find the Four Knights of the Apocalypse, destined to bring about the world's destruction or salvation.

Percival embarks on a journey across the kingdom of Britannia, encountering allies and enemies alike. Among his companions are Donny, a skilled archer with a cheerful demeanor, and Nasiens, a mysterious alchemist with a tragic past. Together, they navigate a world filled with political intrigue, ancient prophecies, and powerful magical forces. The Four Knights of the Apocalypse are prophesied to wield immense power, and their identities remain shrouded in mystery, with Percival being one of the key figures tied to this destiny.

As the group travels, they uncover the truth about the Holy Knights, the ruling class of Britannia, and their connection to the apocalyptic prophecy. The Holy Knights, led by figures like Ironside, seek to control or eliminate the Four Knights to maintain their dominance. Percival and his friends must confront these powerful adversaries while grappling with their own personal struggles and the weight of their destinies. The narrative explores themes of friendship, sacrifice, and the struggle between fate and free will, as the characters are drawn deeper into the conflict surrounding the prophecy.

The story also ties back to the original series, with references to characters like Meliodas and Elizabeth, whose actions continue to influence the world. The legacy of the Seven Deadly Sins looms large, as their choices and battles have shaped the current state of Britannia. Percival's journey is not only a quest to fulfill his destiny but also a search for identity and purpose, as he learns about his lineage and the role he must play in the world's future. The series balances action, adventure, and emotional depth, building on the rich lore of its predecessor while introducing new characters and challenges.