In Spain, Timo the little sailor finds an old map drawn by a child, and certainly linked to the shipwreck of a galleon, three hundred years before, near Isla Raza. So the boy decides to go to the Caribbean on board his little sailboat Rosetta, hoping to find the treasure. On Isla Raza he meets Plato, a boy of the same age and a descendant of the old pirates of the island. Together, based on the clues of the map, they begin to search the treasure. They'll find it, in the end, but it is very different from what they have expected. Meanwhile, someone wants to occupy the small island chasing off the natives. But there is a treasure involved...