Director Peng Sanyuan (right) and actor Andy Lau appear at a Beijing event for Lost and Love, a movie highlighting the issue of child trafficking in China. [Photo by Jiang Dong/China Daily]

Peng hopes to express more than just sadness, she says.

"The movie is also about love and belief in hope," she says.

"A good movie will not just make you cry, but also make you laugh and think."

Peng wrote a draft screenplay in 2013 after two years of research. She met more than 100 people, including victims－those who lost their children and those who were abducted during childhood, police and those who helped to find lost children.

She was then hit by a flash of inspiration. She decided that Hong Kong actor Andy Lau, well known for his cool and suave screen image, should play the lead role.

"I admired Lau's performance in the art-house production A Simple Life," Peng says. "He is like a rich mine－the deeper you dig, the more you find. He is loaded with a lot more than good looks."

However, when Peng put her casting ideas to her boss, Wang Zhonglei, co-founder of the entertainment giant Huayi Brothers, he was "scared", she recalls.

"I thought she was crazy," Wang recalled at a media event. "Lau is regarded as a film god. There was no way such a cool star as him was going to play an embittered farmer."

Peng signed a contract with Huayi in 2011, marking the start of her career transformation from a scriptwriter to a producer and director.

Although Wang rejected her idea, she called Lau's agent to see if he was interested in the movie.