It is hoped the singer and actress will take the message directly to the people who matter -- those who buy rhino horn.
Fighting back tears as she stares at a decomposing rhino carcass in the world-renowned Kruger Park, she vows to use her star power to ensure rhinos are not eradicated by poachers.
"People back home need to learn that we need to keep these animals for future generations and not let them disappear," said the artist, who also appeared on screen in the "Quiet American."
Conservationists hope she and others -- like Chinese-American actress Bai Ling of "Lost" and "The Crow" fame -- will reach Asian consumers who buy the rhinos' horns.
South Africa's fight to restrict the supply of horn has seen military-style anti-poaching operations, but the use of drones and strong-arm tactics has yielded few results.
Over 700 rhinos have been killed in parks across South Africa this year.
Kruger Park has been worst hit, forcing the authorities to approve a plan to relocate hundreds of the endangered animals before they are slaughtered.
- Targeting the consumers -
Now conservation groups want to tackle demand.
As Hong Nhung and investigators comb the gruesome scene, it is likely the horn has already been smuggled out of the country en route to Asia.
"Vietnam is the main conduit" for smuggled horns to the continent, said Andrew Peterson, the head of Rhinose Foundation, the group who brought Hong Nhung to South Africa.
The horns, made up of a substance similar to human fingernails, are a prized commodity in Vietnam and other east and southeast Asian nations.
They are used in traditional medicine to "cure" diseases like cancer.
But even in Vietnam the battle to reduce supply is lagging.
Customs officials have so far this year seized only one consignment of horns, compared to six in 2013.
Stricter checks might have caused dealers to change tactics. The horns, usually hidden in luggage, enter the country already chopped into pieces.
Top Vietnamese customs official Nguyen Hung Anh, the vice-president of the anti-smuggling and investigation unit at Vietnam Customs, has also been flown across the world to witness the horrors of poaching.
That kind of investment may just pay off.
Nguyen said his government was considering tighter regulations to curb the trade.
In Vietnam rhino poaching is classified only under prohibited goods and offenders often get off with light sentences.
"The Vietnamese government recognises the impact of the illegal, we believe that stricter punishment is required," he said.
"Right now government is in the process of drafting a law that would give harsher sentences to people selling the horn," he said.
But he admitted that dismantling traditional beliefs around the use of the horns was the biggest challenge.
According to Nguyen, the horn is a "status symbol" among the wealthy who drink it as a detoxing agent, after it has been ground to powder.
"It's like a owning a diamond," he said, adding that "stricter laws and education are key."
Pop star Hong Nhung hopes she can play a role in that.
"We are going to help spread the message that using rhino products is bad, because animals are killed in this horrible way," she said.