In the final episode of this groundbreaking scientific study, Liz Bonnin and a team of scientists reveal the secret language of our cats, the surprising conversations they have when we are asleep, and why they meow to us but not each other. We rig a house with cameras and cat trackers to discover if four cats living under one roof all get on as well as we would like to think. And we find out why living alongside us is making life difficult for our 21st-century cats.

The second episode of this unique scientific study reveals the wild side of pet cats. Using GPS trackers and cat cameras, they show how these felines transform from pampered pet to purring predator as soon as they leave the cat flap. Liz Bonnin and some of the world's top cat experts put Ozzy and Smudge under surveillance to find out who is king of the street and reveal why, no matter how hard we try, we can't keep our cats' hunting instincts under control.

Playful pets, fearsome fighters or deadly hunters? Millions of us have cats in our homes, yet we know very little about them. In this series, Liz Bonnin joins forces with some of the world's top cat experts to conduct a groundbreaking scientific study. With GPS trackers and cat cameras, we follow 100 cats in three very different environments to find out what they get up to when they leave the cat flap. In the first programme we discover how our cats see, hear and smell the world with the senses of their wild ancestors, and why this could be making life difficult for them in the modern world.

Over the last few years, our weather in Britain has become more extreme. Last winter was the wettest ever recorded, as deadly storms battered the country for weeks on end. But previous winters have seen bitter lows of -22, as Britain was plunged into a deep freeze. What everyone wants to know now is: why is our weather getting more extreme, can we expect to see more of it in the future, and has it got anything to do with climate change? In this episode of Horizon, physicist Dr Helen Czerski and meteorologist John Hammond make sense of Britain's recent extreme weather and discover that there is one thing that connects all our recent extreme winters - the jet stream, an invisible river of air that powers along 10 km above us. What's worrying is that recently it has been behaving rather strangely. Scientists are now trying to understand what is behind these changes in the jet stream. Helen and John find out if extreme winters are something we may all have to get used to in the future.