High on a misty mountainside, red panda cubs Popo and Ketu live happily with their mama. As the sisters grow, they promise Mama that they will always stay close to home. But while cautious Popo is content to spend her days in the family's cosy treetop nest, bold Ketu dreams of excitement and exploration. So when Ketu creeps off down the mountain in search of adventure, Popo must make a choice: will she keep her promise to Mama, or look after her sister?