The Straw Hat crew salvages a treasure chest from a sinking wreck, inside which they find an old lady. To get the pirates to take her home, she promises them the treasure of a golden crown on her island: Mecha Island. Upon arrival, the crew is attacked by the lord of the island but he has a change of heart and decides to seek their help to solve the mystery of the Golden Crown.

(Source: ANN, edited)

The movie is a retelling of the Drum Island arc with new music and animation. Vivi has been removed from the plot while both Nico Robin and Franky, who joined the crew after the Drum Island arc, have been added. The movie also has the Straw Hat's new ship, the Thousand Sunny. It has been stated that Oda will be creating a new character for this movie, Wapol's older brother, Mushul, who also appears to be a Devil Fruit user. 

(Source: Wikipedia)

Upon hearing news that islands in East Blue are being destroyed, Monkey D. Luffy and his crew go to investigate. On their way, however, an outlandish pirate ship appears out of the sky, helmed by the infamous pirate Shiki "the Golden Lion"—a man who ate the Float-Float Fruit and the first ever prisoner to escape from Impel Down. In his quest to defeat the World Government, Shiki kidnaps Nami to be his own navigator and sends the rest of the Straw Hat Pirates to his floating islands as hostages, leaving her in a dilemma. Separated in a land under Shiki's absolute control, Luffy and his crew must survive the mystifying terrain in order to bring back their navigator and friend.

[Written by MAL Rewrite]

The Straw Hat Pirates enter the rough seas of the New World in search of the hidden treasures of the Pirate King, Gol D. Roger－One Piece. On their voyage, the pirates come across a terrifying, powerful man, former Marine Admiral Z.

Z is accused of having stolen the "Dyna Stones", weapons believed to have the power to shake up the New World. The Marine Headquarters believes Z is about to use it to end the pirate era, and with it, the lives of many innocent people. In fear of such a phenomenal event, marines start to take action against the former admiral.

Even if it means stumbling upon marines and the navy, the Straw Hat Pirates decided to chase after Z and stop him from causing havoc. As they continue to embark on their ventures, the pirates bump into new and familiar acquaintances.