Set mainly in and around the Shanghai Ghetto in Japanese-occupied Shanghai during the Second World War, the film tells the story of three children. 

Rina and her younger brother Mishalli are Jewish refugees who escaped Europe but are without their parents. A-Gen is a Chinese boy who meets Rina and helps her and her brother to survive. 

The children form strong friendships and have adventures as they try and fend off the Japanese army occupying the city, and their allies, the Nazis. In the background, the Second Sino-Japanese War takes place, while the children must face the uncertainty that concerns the fate of Rina and Mishalli's parents in Europe.