Cast members of the film Lost and Love (from left to right) Andy Lau, Ni Jingyang, Peng Sanyuan, Liu Yase and Jing Boran attend a premiere ceremony of the film. [Photo by Jiang Dong/China Daily]

Unexpectedly, Lau quickly agreed.

"I was born in a rural area of Hong Kong," Lau says. "When I was a child, my dream was to be a farmer. The thought never crossed my mind that playing a farmer was something I could not do. I've done a lot of research on the kinds of gestures farmers make, such as squatting to eat food."

As Peng told her crew, making the movie is about more than a job.

"I think it's a citizen's duty to raise awareness of this sensitive topic," Peng says.

The thriving black market in child trafficking in China is widely believed to be fueled largely by the demand of buyers who want more children.

The maximum penalty for traffickers is execution, but those who buy abducted children generally get off scot free unless they have abused the children or tried to prevent them from being rescued.

A revised law draft made public in October proposed that those who harbor abducted children be criminally liable.

"If the laws are changed, even as a result of the minor influence of my movie, for me that will be a bigger thing than making money and winning prizes," Peng says.