In order to save grandma's garden, 10-year-old Arthur (Freddie Hammer Freddie Highmore) must find the treasure that Grandpa left before he disappeared. According to the tips left by her grandfather, Arthur finally found the moonlight door that only opens once a year, entered the Mini Ink Kingdom, and met the beautiful Princess Zelena and the Mini Ink in Grandpa's notes. it was learned from them that Grandpa walked into the taboo city four years ago in search of treasure, and the "evil M" ruled there. Arthur drew the sword of power from the stone while fighting the intruding enemy and became a hero of the mini-Mo kingdom. When the sword is pulled out, the heroes of the Mini Mohist Kingdom must go to Necropoli, the Tabu City, to defeat the "Evil M." Arthur, Princess Zelena and Prince Beta overcome many difficulties and finally arrived at M's lair, where the legendary demon Matazad lives. This film is Luc Besson's tenth film, and it is said to be his "harvest". It took seven years of preparation and production, with an investment of 65 million euros, making it the most expensive work in the history of French film production.