Warning: this video contains graphic images of a lion being shot.
A whistle gets the lion's attention just before the shots ring out.
There's nowhere to escape. Bred in captivity, and hunted in a confined area, trophy hunters pay up to $50,000 to shoot them. It's called a canned hunt.
Derek Gobbet filmed one such hunt, but was so appalled by what he witnessed that he felt compelled to speak out.
"Eventually this poor animal is shot and dragged out of a hole. It's not something anyone can really be proud of in my book," Mr Gobbet told CBS.
"It's all just a lie."
Canned hunting is a multimillion-dollar industry in South Africa.
It's completely legal, but under increasing scrutiny.
Kevin Richardson, who used to work on a lion farm, has rescued more than two dozen lions also destined for canned hunts.
"Most people think lions are terrifying creatures, but in actual fact it's the lions who are terrified in a canned hunt," he told CBS News.
Mr Richardson developed such an unusual bond with these animals on the lion farm where they were raised that they now seem to regard him as part of the pride.
He was horrified when he arrived at work one day to find they had been sold for canned hunts.
It was a turning point for him, and he spent the next four years raising several hundred thousand dollars to buy the lions back.
"We need to outlaw the practice of canned hunting... and make sure no one crosses that line," he says.