The Straw Hats, having been left by Robin, uncover the real motive behind the actions of the CP9 assassins and try to stop them from using the most destructive weapon of the ancient world.

Luffy, working with Usopp to repair the "Merry-Go," faces a tough decision when his money is stolen and he has to determine what will happen to the ship.

Nico Robin is blamed for the attempted assassination of the mayor of Water 7, and the Straw Hats try to clear her name while uncovering information that the members of CP9 might be the real culprits.

"Sanji, Usopp and Franky are on their own against the Navy as the rest of the Straw Hats hurry to catch up to the speeding Sea Train. But freeing Robin from the clutches of CP9 won't be an easy task with a train full of enemies. And even if they do reach her, does she even want to be rescued?"--P. [4] of cover.

In order to save Robin, Luffy must get past the deadly assassin Rob Lucci. The rest of the Straw Hats are engaged in their own battles to find the special key that will release Robin from the tower.

The Straw Hats lose control of their ship and end up on an island full of zombies known as Thriller Bark, where they become the targets of the dreaded Gecko Moria.

The Straw Hats need a special key to release Robin from the Tower of Justice where she is held captive. One of the CP9 assassins holds the right key but Luffy and his crew may have to defeat them all to save her.