Hong Kong director Pang Ho-cheung moved to Beijing two years ago and persuaded scriptwriter Luk Yee-sum to come with him.
The duo wanted to set their new film in the mainland but didn`t discuss the plotline. Instead, they hung out at restaurants, bars, parks and friends` homes in the capital.
One day in Chaoyang Park, they saw many elderly people holding up signs introducing their children. Some wrote: "My son looks like Tony Leung". Others read: "My daughter resembles Zhang Ziyi."
They were trying to find boyfriends or girlfriends for their children.
Pang and Luk found the scene interesting and included it in their film Love in the Buff.
The film is a sequel to Pang`s 2010 Love in a Puff, a romantic comedy set in Hong Kong. It tells the story of two young people, who develop a relationship during their daily cigarette breaks after Hong Kong banned public smoking in 2007.
The film was a smash hit, especially among youths. At one point, Cherie Yu, the heroine, gives her e-mail address to her lover, Jimmy Zhang.
One day, Pang opened the e-mail box he had created for the character and was surprised to find there were many mails from viewers. They wrote to share their opinions on the characters` relationship and how they hoped the story would continue.
Pang was moved. He considered shooting the sequel in Beijing.
The mainland market has become alluring to Hong Kong filmmakers, who experienced a radical decline of the industry in the late 1990s and witnessed the rapid growth of the mainland`s box office in recent years. It reached 1.3 billion yuan last year.
Jimmy and Cherie break up in the sequel`s beginning. They move to Beijing to start new careers, as do many Hong Kong residents, such as Pang.
They find new lovers in the city - only to discover it`s hard to forget each other.
The film required finesse because many believe films co-produced by mainland and Hong Kong turn off both audiences.
Some Hong Kong filmmakers lack real-life mainland life experience, so their films don`t do well with the audiences they`re portraying while losing Hong Kong audiences, too.
Pang tried to win both over.
The 39-year-old and his wife moved to Beijing two years ago and lived in the city most of the time.
He initially struggled to adapt to the dry climate and frequently suffered nosebleeds. The food was too spicy, too, he says. He was advised to eat pears and honey, and put a wet towel on the chair in his room to increase humidity.
But he made new friends, such as local filmmakers Feng Xiaogang and Ning Hao. He can recite some Beijing jokes in his broken Mandarin.
"If you don`t live in a place, how can you portray its life and people?" he says.
The film is a thigh-slapper in both Cantonese and Mandarin.
Pang strongly recommends viewers see the Cantonese version.
He wrote the script in his native tongue, and many jokes are linked to the dialect.
It`s an unavoidable pity some witty jokes are lost in translation. But Pang is confident about both versions.
"Many comedies make people laugh through the use of language, so they only work for people who live in a certain language environment," he says. "But I tried hard to make my film funny by virtue of its structure and with stories that relate to as wide an audience as possible."
An example of this is when Cherie agrees to a blind date with a man whom she is told looks like Robert Pattinson`s Chinese counterpart Huang Xiaoming, but suddenly gets sick. So her unattractive friend pretends to be her and goes in her stead. She and the man marry later. The man really does look like Huang, and Pang invited Huang to make a cameo.
"Even if the audiences cannot understand Cantonese, 80 percent of the jokes still work for them," Pang says.
He has been trying to persuade mainland theaters to screen both versions.
"Theaters should at least provide the option and then decide how to allocate the versions according to ticket sales," he says.