At an age when perhaps friends mean more than moms, 10 year-old Sun is an outcast at school. During summer vacation, she meets Jia, who is new to town. As Sun shows Jia around the neighborhood and they play at each other’s houses and share secrets, they become best friends. However, when the new semester starts, Jia notices a strange vibe between Sun and the other kids. Jia tries to get into the cool kids group and starts to distance herself from Sun. The World of Us pays a visit to the complex and delicate world of children.