While heading to the next island, Zou, Luffy’s appetite causes them trouble and he and Bartolomeo find themselves entangled in the scheme of a pirate lord who can manipulate silver.

The Tram-Man arrives! And has Luffy, Bartolomeo and Desire on the run! The deeper the three fall into the pit, however, the more clear it becomes that Bill's group hides a terrible secret!

Inside the underground mines, Luffy and Bartolomeo are attacked by the Rail Car Man Avelon. Desire is attacked as well, which shocks her, as Bill had rescued her crew after it was destroyed. The three are then sent plummeting further underground, where they discover members of the Silver Pirate Alliance who are enslaved as miners due to not pleasing Bill. Bartolomeo manages to free his hands, and Avelon returns, unwittingly freeing Luffy from his silver ball with an attack. Luffy and Bartolomeo then work together to defeat Avelon, and upon hearing about this, Bill orders the underground mine to be buried.

The Straw Hats meet a girl named Olga and travel with her to Alchemi in the pursuit of Pure Gold, but are pursued by the Marines and the treasure hunter Mad Treasure.

Luffy, Desire, and Bartolomeo go up against Bill! But the mad, Smelt-Smelt man becomes deranged and lets his true power unfurl! Do Luffy and the others have any hope of exposing Bill's self-serving aims and turning his gang against him?