Sonia, an introverted thirteen-year-old girl, suffers from a disorder that prevents her from breathing deeply. Raised in a messy family, she doesn't find the support she needs in the delicate transition between the end of childhood and the beginning of adolescence. While a part of her little world rejects her - her school friends, her boyfriend - she meets Daria, a slightly older and much more self-confident girl, who offers her friendship.