Impel Down Arc

This twenty-first story arc, the third leg of the Summit War saga, abandons the crew's reunion to follow Luffy alone as he breaks into the great undersea prison. Slipping inside with Boa Hancock's help, he races against Ace's scheduled execution through a fortress of escalating horrors and unexpected alliances.

With Ace held below and his execution looming, Luffy stows away in Hancock's robes to enter the prison undetected, leaving her behind at the upper gates. Inside, he tears through the early levels, reuniting by chance with old foes like Buggy and Mr. 3, who reluctantly become temporary allies amid the chaos of bladed forests and beast-infested floors. As he descends toward Ace, he gathers a ragtag band of escapees and prisoners, while the warden Magellan and his venomous powers stand as the prison's ultimate guardian.

The deeper Luffy goes, the worse the odds: Magellan's Poison-Poison abilities nearly kill him, and Ace is moved before he can be reached, transferred toward the coming war at Marineford. Luffy is saved from death by the okama Emporio Ivankov, a Revolutionary leader hidden in the prison's depths, whose hormone powers haul him back from the brink. Rallying allies including Crocodile, Jinbe and Mr. 1, Luffy mounts a mass breakout, fighting upward against guards, the Blackbeard Pirates who arrive to claim the prison, and Magellan himself.

Though Luffy fails to free Ace before the prisoner is shipped off to execution, he succeeds in shattering Impel Down's reputation for inescapability, leading the largest jailbreak in its history. Bonds forged in the descent, with Jinbe, Crocodile, Ivankov and others, carry forward as Luffy commandeers a Marine ship and sets course directly for the battlefield of Marineford, determined to reach his brother before the axe falls.