In 1800, at a girls' school in Venice, isolated and supposedly mute domestic servant Teresa discovers the joy that music can bring, teaming up with a group of talented girls.

Jack has always wanted a little brother to play with, and when Gio is born, his parents tell him his brother is a "special" child. That's when Gio turns into a superhero with amazing powers in his big brother's imagination, like the ones in his comic books. Over time, however, Jack learns the truth: his brother has Down syndrome, a condition Jack decides to keep secret. When he goes to high school and falls in love with Arianna, he hides Gio's very existence from her and his new friends. But how can you expect someone to love you if you conceal such an important part of yourself? In no time, the truth comes out, and Jack realizes that Gio's energy and vitality are contagious. Gio's original outlook does indeed change the world, just like a superhero.