Xu Jinglei (left) alongside Nick Cheung promote his directorial feature The Trough. [Photo provided to China Daily]

The story is about an undercover police agent, whose identity is brought to light for being drawn into a child kidnapping case. To pursue justice, he risks his life to locate the top villain while running from the gang's killers.

Asked about his shift from acting to direction, Cheung said, "Although I have worked as an actor for many years, the new movie is a breakthrough for my career. I've accumulated experience about direction over the years. And now I want to use what I've learned from film sets for my own work."

Yu Dong, president of the movie's financer, Bona Film Group, said the ticket sales are very optimistic for the coming Labor Day holiday, a significant box office season in China.

Cheung stars as the police officer; among the rest of the cast are A-list actress Xu Jinglei, television host-actor He Jiong and award-winning actress Yu Nan.

Xu, who also appeared at the Beijing press conference, revealed her role is the "mysterious big boss behind the criminal world".

"I play opposite Cheung's character, but we (the two characters) have a more subtitle relationship," says Xu, who collaborated with Cheung for the first time.