Luffy and his crew embark on a quest to a mysterious island in pursuit of a fabled sword, renowned as the world's most valuable. As they encounter hostile marines and captivating maidens, the group finds themselves divided. Amidst this turmoil, Zoro's loyalty wavers as he chooses to aid a childhood comrade. Meanwhile, Luffy and Usopp navigate a treacherous cave, while the remaining members rally to assist a village in a battle against the marines. A confrontation between Zoro and Sanji unfolds, leading to Zoro acquiring the crucial pearls, the sole protection against a malevolent sword capable of shrouding the world in darkness.