"M. The city in the center of the world" continues the adventure of our characters right where we leave it in the first chapter of Nubla. Once they reach the new continent, the two children trapped inside this universe of paintings must begin the search for the city of M., the place where they can return the memory to that world, which has now lost it. The city is not in a physical place and can only be found beyond dreams. The trip will undoubtedly be difficult and dangerous for our protagonists, who will not only have the help of "Nubla" the elephant to achieve their goal, but with many other characters and inhabitants of that world that they will find in their path.