Mei Yu has been working her whole life to go to Yale. It has been her dream since she was six. But when her sister is diagnosed with cancer and her mother is stuck working day and night, she takes it upon herself to care for Katie. Mei Yu tries her best to be cheer up Katie, but Katie is lonely with no friends. That was when, one day Mei opened her window to find a pony, in a nest? She takes the small pony known as Celestia, or nicknamed Tia by Katie.
Mei sees Celestia as a burden, but Celestia slowly brightens Katie's life, and Mei's. But thanks to her nosy apartment neighbors, the government wants to take away the pony for experiments. But, Mei and Katie won't let that happen.