Quick recap
The seventh film, non-canon. The crew rescues Roba, an old woman stuck in a chest at sea, and agrees to take her to Mecha Island in exchange for the Golden Crown, a legendary treasure. There they learn the island is a colossal turtle and that Ratchet, Roba's son, wants to control it with his mechanical castle and rule the world. The Straw Hats decode an old folk song holding the island's clues. Luffy wrecks Ratchet's best robot, and the crew teams up to bring down the castle and free the turtle. The Golden Crown turns out to be the golden shells of her hatching eggs.
No spoilersOpens once you mark the title as seen.