A group of pirates lead by Alvida plunder a ship, only to find a barrel which contains a strange boy named Luffy. Luffy is on a mission to find the legendary treasure "One Piece" and he befriends the ship's cabin-boy, Coby, who actually wants to become a marine officer. Luffy defeats Alvida and the two journey on in search of crewmates.

Out on the sea, Luffy almost loses his hat and reflects on his past, and how a pirate named Shanks influenced him. Afterwards, Luffy meets Nami, and Buggy the Clown's men.

In order to save herself and steal a map to the Grand Line, Nami tricks Luffy into allowing her to turn him over to Buggy.

Nami form an alliance becoming the navigator of the crew, but not a full member yet. They arrive in Syrup Village looking for a suitable ship. On this island they know the liar Usopp, who also has ties to the Shanx.

When trying to convince his rich friend, Kaya, to give the Straw Hats a ship, Usopp is told to stay away from her by her caretaker, Klahadore. However, when Usopp and Luffy later see him conversing with a strange man, they learn of a plot to kill Kaya.

After learning of Captain Kuro's evil plan, Usopp runs back to the village to warn Kaya, only to find that after all his years of lying no one believes him.

Usopp resolves to keep his story of pirates attacking the town a lie by making sure none reach it. Luffy, Zoro, Nami, and Usopp then try to keep the Black Cat Pirates at bay.

The Straw Hats manage to take out most of the opposing Black Cat Pirates, so Jango orders the Nyaban Brothers to attack. Meanwhile, after getting hypnotized by Jango, Luffy gets himself stuck under the collapsed mast of the Black Cat Pirates' ship.

Captain Kuro himself arrives at the scene, and with Zoro too injured to fight, Luffy being incapacitated, and the other two being too weak to handle him, things seem hopeless. However, Kaya herself appears to bargain with Kuro.

Zoro and Buchi (of the Nyaban Brothers) face off once again as Luffy and Kuro begin their fight. Usopp orders the Usopp Pirates to run away with Kaya, but Jango goes after them. A flashback reveals how Captain Kuro faked his death with Captain Morgan and how he became Kaya's butler.

As the fight between Luffy and Kuro is close to an end, the Usopp Pirates do their best to avoid Jango.

Kuro's ultimate attack, "Shakushi", attacks everything in the area, whether friend or foe, and Luffy becomes enraged by his lack of regard for his crew. Will Luffy's determination overcome Kuro's sheer speed?

While Usopp & Luffy fool around with the ship's cannon one day, Zoro dreams about his childhood and the promise he made to Kuina.

The crew meets Johnny and Yosaku, Zoro's former companions, and they set sail for the Baratie restaurant in search of a cook.

Sanji, a cook at the Baratie, helps a starving pirate named Gin. Luffy begins his job as a waiter to pay for the damage he did to the Baratie, and tries to convince Sanji to join his crew.

Gin returns to the Baratie with his also-starving captain, Don Krieg, to whom Sanji once more gives food, but Don Krieg betrays the cook once he regains his energy.

It is revealed that Chef Zeff was a great pirate known as Red Leg Zeff. Gin explains the catastrophe the fleet met in Grand Line when they encountered Hawk-Eyes Mihawk, and Krieg attempts to take control of the Baratie.

Gin finishes off Pearl, claiming that he wants to kill Sanji himself. Still wounded, Sanji faces Gin while Luffy attacks Don Krieg.

When Gin refuses to kill Sanji, Krieg uses a poison gas on him. Luffy seems to have the advantage in the fight until Krieg pulls out his explosive Battle Spear.

Even after taking several hits from the Battle Spear, Luffy refuses to give up.

After the battle, Gin decides to go back to the Grand Line with Krieg despite still being poisoned, and Sanji makes the difficult decision on whether to stay or to go with Luffy just as Yosaku comes back with news that he knows where Nami is.

Luffy and friends land on Little Garden, a prehistoric island inhabited by dinosaurs and giants.