The Straw Hats plan to divide and conquer, with one group heading to save Sanji and the others heading to the Land of Wano, but in the final moments before their departure, the tremendous elephant island begins to quake.
The Straw Hats and the others split up into four teams, each on different missions; some from the Mink Tribe insist on leaving with Luffy's team; Usopp makes a weapon for Nami that seems to work like magic.
The Straw Hats set out from Zou on their way to win back Sanji and discover one more crew member than they should have; the leading families and leaders of the world make their way to Mariejois for the pivotal world meeting.
News of the raid on the Revolutionary Army reaches Luffy; the crew faces a storm and a sudden lack of provisions; Emperor Kaido, furious at Joker's capture, fumes with anger at the reckless generation of upstarts.
Robin, Rebecca, and Bartolomeo draw closer to the Flower Field on the fourth level of the Royal Palace, but Gladius' exploding spheres send Robin and Bartolomeo crashing towards level three- and directly into battle with the creepy Headcracker Dolls.
As word of the Straw Hat resurrection spreads through the Navy, Luffy and his crew get acclimated to their underwater environment, and Franky reveals the startling identity of the man who protected their ship.
The Straw Hats finally make it to Fish-Man Island, but their reputation precedes them, leading to trouble with the New Fish-Man Pirates. Only a daring maneuver can get them out of hot water, but there's no guarantee they'll survive.
After two generous donors save Sanji from death by nosebleed, Luffy and Usopp take a tour of the island. But their welcome is worn out when a mystic mermaid has a terrifying vision - that Fish-Man Island will be destroyed at the hands of a Straw Hat.
A trio of unsuspecting mermaids find themselves in hot water after releasing a bad guy from his barrel of a prison. Over at the royal palace, Luffy gets up close and personal with the Mermaid Princess.
With their backs against the wall, the Straw Hats are forced to take King Neptune and his men hostage. On the other side of the palace, Luffy and the Mermaid Princess make plans to visit the Sea Forrest.
Luffy, Chopper, and Sanji are taken prisoner by a fish mob just as Vander Decken launches an attack on the princess; Zoro continues his battle with Hordy; Nami hitches a ride on a mermaid to escape the crumbling palace.
In the wake of Fisher Tiger's tragic death, the once-mighty Sun Pirates are splintered by an ongoing quarrel between Jimbei and Arlong; Queen Otohime's ceaseless quest to help her people begins to take its toll.
Tensions run high when a slave-owning Celestial Dragon washes up on Fish-Man Island; his former captives cry for out for blood, but Queen Otohime sees it as a chance to mend fences between the gilled and non-gilled.