'You want girls? Come back when the police let them go'
It is 12.30am. This is the seedy side of Hong Kong. But tonight the notorious red-light district of Mongkok is eerily quiet.
Police are raiding brothel after brothel. They have already arrested 47 mainland prostitutes and four pimps.
They are acting on fresh intelligence reports that the pimps are using new and innovative ways to ply the flesh trade.
Our mission, too, has been inspired by these same reports.
It is a very different mission for the dozens of men who shift in the shadows, skirting the neon-lit sidewalks or waiting in parked cars in back streets.
It has been claimed that pimps are using the latest mobile phone technology to show a 'photo album' to potential clients.
But with the streets so subdued, instead of thronging with night-walkers, pimps and prostitutes, it is hard to tell what the reality is.
Suddenly we find ourselves in the middle of another raid.
Police lead a gaggle of mainland prostitutes out of a food court, their heads bowed and hands touching shoulder-to-shoulder. The arresting detective tells us how they are checking out the latest reports. He has heard that some pimps may be using phones to sell sex. He confirms the use of illegal two-way radio handsets, and points to the seizure of some of these devices during the night.
Down the road, inside a brothel, a pimp shrugs his shoulders when asked if he has any girls. 'They have all been arrested,' he says.
'You will have to come back at 5am when they get let out of jail.'
He is suspicious. He fidgets with his phone and slides it into a desktop drawer when asked if he has heard of pimps using them to sell sex.
Mongkok police chief To Chun-wai later tells of the traditional methods used by pimps to offer the services of their workers.
'Mongkok has a certain reputation. It is very compact and convenient and a hub of entertainment,' he says.
'The prostitutes' customers usually go straight to vice establishment to see the talent for themselves or they might get enticed to go inside by the girls hanging about on the street level.
'We have found cases where they can look up a photo album on the internet.'
He said the pimps were the guardians of street hookers and managed an average of five girls each.