The Thriller Bark Arc is the eighteenth story arc in the series, and the first and only in the Thriller Bark Saga.
The Straw Hats, during their journey into the Florian Triangle arrive at a haunted island/ship called Thriller Bark, in which their shadows are stolen by Warlord of the Sea Gecko Moria and must hurry to get them back before the sun rises. After defeating Moria, another Warlord shows up to make the Straw Hats' situation worse. The Straw Hats also gain a new crewmate, a living skeleton named Brook who becomes their musician.
The Marines are convinced the Going Merry is a ghost ship after it crashes inside their fortress from above. The crew members are scattered around the premises.
In disguise, Sanji shows the Marine chefs the proper way to prepare a meal.
Zoro is taken prisoner as Chopper and Nami assist a nervous doctor in treating injured Marines.
Robin and Usopp both disguise themselves as the same visiting inspector, and Usopp is thrown in the brig with Zoro. Luffy and Sanji are discovered by Jonathan after a slight mishap.
The real Inspector is thrown in the brig with Zoro and Usopp, while Sanji and Luffy race to rescue the two while avoiding detection.
Sanji and Luffy, after freeing Usopp and Zoro, try to escape Navarone. As the Burning Soul combat unit is deployed, Dr. Kobato leads Nami and Chopper to the docks.
The crew meets at the docks and are surrounded by Marines. Using Nami as their fake hostage, they trick the Marines into letting them back on the Going Merry.
The crew disguises the Going Merry as a Marine ship so they can get their treasure back. With the gold, they decide they’ll hire a shipwright.
Usopp splits up the crew into two teams: the gold retrieval team and the waver retrieval team. Inspector Shepherd decides to catch Luffy on his own.
Luffy, Zoro, Usopp, and Robin continue to search for their treasure. Sanji leads Nami to the captain’s quarters where they retrieve their gold.
The Going Merry is grounded during a period of low tide and Jonathan believes they’ve reached “checkmate”. They cleverly use the impact dial to boost the ship and the breath and flame dials to inflate the octopus balloon again so they can escape.
Luffy and company come across a mysterious pirate ship after trying to escape a giant wave. Soon, they arrive on an island inhabited by strange animals. Going Merry is captured by the Foxy Pirate crew.
After Tonjit re-unites with his horse, they are soon attacked by Captain Foxy and his subordinates, who challenge Luffy in a Davy Back Fight, a contest of pirates where the stakes are members of the crew.
The first round of Davy Back Fight involves a race around the island with tiny boats. Zoro's and Chopper's boat is eliminated.
With only Luffy, Nami, and Porche's boat remaining, it's an all out war to the goal, but after Foxy exposes his Devil Fruit powers, Porche wins and takes Tony Tony Chopper from Luffy. The second round prepares to start.
Without Chopper, Sanji and Zoro must face the Foxy Pirates in a ball game, but are hampered by their blatant cheating and the crooked referee.
The bickering rivals Sanji and Zoro manage to overcome the opposing team by working together. Luffy chooses Tonjit's horse, Sherry over Chopper.
The Straw Hats face Foxy a race around a giant ring on roller skates.
Thanks to some quick planning, the Straw Hats win the race.
With Luffy's victory, he takes Chopper back, but foolishly accepts another challenge by Foxy.
Foxy decides to take Robin from Luffy this time because of her Devil Fruit ability. The next match is a race to the top of the island.
With Chopper gone again from Luffy's crew, Luffy and Foxy face off in the final game: a battle of brawn aboard Foxy's ship.
Luffy continues to battle Foxy with the odds not in his favor, and the fight continues inside Foxy's ship.
Luffy manages to finally defeat Foxy by using his ability against him. After dismissing his new crewmembers, the Straw Hats leave in search for a shipwright.
A mysterious figure appears during the night and steals the memories of the crew. In the morning, Robin is the only one who remembers the Straw Hats adventures together. Her attempts to keep the crew together fail as Nami and Zoro go separate ways.
Robin suggests that only those who were sleeping lost their memories. Luffy and the others then remember seeing the mysterious boy who played some kind of flute. Later that night, they discover the boy outside and Luffy tries to fight him. At the last second, he proclaims his memory has returned.
During the night, Usopp, Chopper, and Sanji question what brought them to the Going Merry. In the morning, Usopp builds them a raft and they sail to the island where they meet Nami again. Meanwhile, the boy sets his sights on Zoro.
On their way to "The Palace of the Sea God" Robin's group meets an entranced Zoro. It looks like Zoro wants to fight so Luffy urges the others to keep going without him. They apprehend the kid but the whistle was what was really stealing their memories. Zoro returns, still entranced, but Luffy's nowhere to be seen.
Luffy returns and knocks some sense into Zoro. Cornered, the sea horse spreads illusions of the people in their memories to distract them. It steals their complete memories and claims that it has become a Sennenryu. Luffy defeats it and returns all the memories but the townspeople are convinced they're the memory stealers.
Luffy rescues Foxy, Hamburg, and Porche from a storm at sea. When they reunite with the Sexy Foxy ship, they find it captained by somebody new. Foxy accepts a Davy Back Fight in order to regain his ship and crew. Donning the afro once again, Luffy vows to defeat the captain.
Once Foxy wins back his crew, he captures the Strawhats. Nami and Luffy fight Foxy and although he's defeated, his crew accepts him back. Later, they sail to an island where they meet someone Robin knows; a Marine named Aokiji.