It's 3am at Kadoorie Farm and Botanic Garden and three shadowy figures clamber down thickly bushed slopes of Kwun Yum Shan (Goddess of Mercy Mountain) towards the animal pens. They carry sacks in their hands and dreams of rich loot in their heads. Their quarry is turtles.
Suddenly, a german shepherd bounds forward, barking furiously. Lights flash on, illuminating cages. Security guards carrying flashlights arrive. The raiding party of poachers flees, stumbling back through the bush. In a solid concrete bunker behind a locked steel door protected by a sophisticated electronic alarm system, several dozen Cuora trifasciata slumber in placid safety. This time, the kam chin kwai (Golden Coin Turtle) have escaped capture; police say raiders fled with 25 turtles in one attack earlier this year.
Kadoorie Farm officials have revamped security several times to thwart determined turtle thieves. Attempts are still made. The reason for such stubborn forays is simple; the attractive turtles are worth huge money, trading on underground markets for up to $350,000 for a mature female.
'Kam chin kwai have three problems,' says conservation officer Paul Crow. 'They're beautiful, superstitious people believe they are lucky pets and quacks say a potion made from them can cure cancer.' The first 'problem' is certainly true.
Mr Crow, who grew up in Hong Kong prowling streambeds looking for snakes and lizards, has a passionate regard for the animals.
Unlocking a huge padlock and lifting a heavy steel covering from a watery pen, he picks up a turtle half the size of a football. The animal sticks its red-striped head out of its shell.
It's a gorgeous creature. It's also, tragically, increasingly rare. Because of intense hunting by poachers who sell to medical fraudsters, Hong Kong is now the sole remaining place where Cuora trifasciata exists in the wild.