Merry Rogers and Gold Monsters

There is an island in the sea that is not on any map. And on that island, pirates seem to be waiting for countless jewels and piles of gold. You can find this place on the treasure map drawn by an old violinist. But the treasure is guarded by a monster that devours pirates and smashes their ships to pieces. One day, while waiting for a letter from her best friend Jim Well done, Matilda snatched a bottle from the sea that contained the same treasure map. Together with the family of Merry Rogers and an eccentric violinist, she goes on a "Black Hole" in search of a mysterious island.
Who will the violinist really be? And what will Matilda invent to defeat the monster, save 92 pirates from its belly, and in addition get rich with treasures and bananas? ..