: The real threat is Douglas Bullet , a legendary former member of Roger’s crew known as the "Demon Heir". He uses his Gasha Gasha no Mi (Union-Union Fruit) to combine inanimate objects into a massive mechanical colossus.
: These episodes follow Luffy as he attempts to restock the Thousand Sunny's cola supply on an island ruled by the Cidre Guild, a group of bounty hunters. He reunites with Boa Hancock, and they eventually obtain an invitation to the Pirate Festival featured in the movie. One Piece Movie 14: Stampede Plot
To set the stage for the movie, the One Piece anime aired a two-episode tie-in arc.
You can find the movie and its prequel episodes on major anime platforms: