HONG KONG -- The tools of his trade may smack of Agent 007 - spy cameras and phone tapping devices - but David Cheung uses the gadgetry to help his clients with an all-too-common predicament.
Cheung runs a detective firm that specializes in hunting down Hong Kong's philandering husbands, many of whom have married second wives in mainland China or taken mistresses there.
Business has been booming as factories move from Hong Kong to mainland China in search of cheaper labor, and a new Chinese law against infidelity will likely keep Cheung even busier.
He's recruiting more staff - adding to his current team of 14 - and is stocking up on more new equipment to catch the cheaters.
Cheung says he's been dealing with more than 10 cases of infidelity per month since China passed its law in April that can force philanderers to pay compensation to spouses or spend up to two years in prison. A year ago, Cheung had just three or four such cases a month.
The straying husbands can be fairly easy prey.
"You send someone to follow the husband to China, and once he steps out of the train station, our team in China will take over and follow him," Cheung said. "Many go straight to their mistress' place. It's not that hard, really."
Many Hong Kong men have long been able to afford more than one woman, and often the second wife or mistress is just across the border.
As factories moved from Hong Kong to mainland China, many businessmen started spending more time there. They found themselves popular with young mainland women desperate to seek a better standard of living.
With China growing so rapidly that more mainland men can behave the same way, officials passed the new marriage law to fight back.
It's not clear how many aggrieved Hong Kong women can take advantage of the law. The legal systems in Hong Kong and mainland China are different. Many people here have no idea how to go to court in China, and most are simply not rich enough to pay for a detective.
Hong Kong's legal aid system won't cover actions on the mainland.
Cheung said he charges around $1,900 per day to track down unfaithful husbands.
Another detective, who only identified herself as Li, said a photograph of a philanderer and his new companion together would cost $385.
"Some women are so desperate they would even sell or pawn their jewelry to pay for the service," said Cheung. Others take out loans, he said.
Perhaps an even bigger hurdle for many victims than money is an emotional one, marriage counselors say.
Some worry about their husbands turning violent, and many try to avoid shame. Although divorce is becoming more common in Hong Kong, many Chinese still consider it a disgrace that extends to the family.
A 54-year-old woman, who would only identify herself as Lam, said she spent a long time tracking down the affairs of her 60-year-old husband.
Lam says she can prove that he fathered a child with a young mainland woman five years ago - but she has yet to file any legal actions because she wants to avoid embarrassing her family.
"I have gathered enough evidence to sue him," Lam said. "But I feel so pained and torn. I don't want to shame my children."
"To sue, you need to be rich," said Paulina Kwok at the Caritas marriage counseling service. "Most wives are struggling to make ends meet already - instead of splashing out on legal cost they need money to bring up their children."
And some husbands disappear, making claims almost impossible.
Despite the difficulties, Lam welcomes the new law.
Even though she hasn't decided whether she'll sue her husband yet, she thinks the law gives her more bargaining power.
"I think the new legislation does work," Lam said. "My husband has been very careful with how he deals with me and has promised to leave his mistress. Well, I just have to wait and see."