Australians love their sport. Australians also love a punt. Right now, Australians love betting on greyhound racing, the sport based on pushing dogs to their limits. With more than 40,000 races and more than 300,000 dogs running at tracks across the country each year, Australians are now wagering $4 billion a year on the sport. Prize-money has skyrocketed and greyhound racing is riding a wave of renewed popularity. The message to punters is that the sport has cleaned-up and modernised; the welfare of animals is now at the forefront of the industry. But things are not as they seem. This week Four Corners reporter Caro Meldrum-Hanna leads a gritty investigation into the darkest secrets of the sport, exposing the gruesome underbelly of greyhound racing. This investigation will rock the industry, and the sport, to its core. Making a Killing reveals widespread cheating and illegality across the country, and throws into question the validity of thousands of greyhound races and millions of dollars. How the cheating is actually done is so extreme it defies belief. What some trainers are prepared to do, to give their dogs the winning edge, will shock even the most hardened viewer. As someone who has looked closely at the sport tells Meldrum-Hanna: "Putting together animals, gambling and prize purses is a toxic mix. It's capable of turning men into monsters." What a small team of investigators with limited resources has managed to uncover in Making a Killing should put the regulators of the industry to shame and change the sport forever.