Having lived in Shanghai for a few years, producer and actress Jane Wu learned that more than 20,000 Jewish refugees had taken shelter in the city after fleeing Europe during World War II.

In 2015, Wu shared the story with Sid Ganis, a former president of the Academy of Motion Picture Arts and Sciences and a veteran Hollywood producer.

"Ganis is Jewish. The story resonated with him, and he believed it could be adapted into a movie," she says in a recent interview to China Daily.