 I'll be going down into the gas. We're going to get killed in gas chambers. The meat industry say it's humane. It's fairly well documented. It's one of the humane methods of slaughter. But when I found out what was really going on, I had to do everything in my power to expose it. So I asked my partner, Tarian, to come along for the journey. And I turned to Dan to go in as an undercover employee. When Joey and I first met, I learned all about his background, how he turned his life around and began his work for animals. Suffering is universal. You can see in their eyes. But everything sort of went up a notch when I come across this notorious gas chamber in Manchester. My security camera's just there. So in the UK, there are charities set up specifically to prevent cruelty to animals. And why weren't more of them speaking out against the use of CO2? Because we're in London, we should go to DEFRA. Do you want to pass a message on that for making a documentary? Do you want to speak to someone from the DEFRA office? Essentially, if we suspect your suspicious behaviour, they do legislation for the meat industry. So we're investigating the meat industry. This cruel and scientifically condemned method by scientists after scientists is now being adopted by the industry. In the UK and internationally, has the humane way to kill pigs. And then the door comes closing down behind the pigs. I can hear them screams. I can see that river of blood. It stays with me. It stays with me every day. I don't think there's any such thing as humane slaughter. Those animals do not want to die. Pigs are naturally very intelligent animals, and they can see what's happening, smell, feel. Man, you're going to be fine. Get out! You're driving off the set. Bye-bye. For months, I studied gas chamber blueprints. In order to expose what was happening to the pigs in the gas, I needed to install multiple cameras inside the chambers. I had to consider so many different variables. Any mistake could be fatal. The tension in the room, you could cut it with a knife. So my heart's pounding. My body was saying, get the hell out of here. My worst nightmare was to be coming through. I'd have to leave it. If I'm not willing to risk my life to expose what's happening to them, then I don't really care about it enough.