From huge dogs to tiny dogs, working dogs to lap dogs, hairy dogs to hairless dogs - the team investigates why this single species comes in so many shapes and sizes. Set in a typical English village, the team uses DNA science to reveal the sometimes surprising family trees of some of the village dogs. The team also find out how the extraordinary genetics of modern dogs underlies the extreme differences we see between breeds. Historian Ruth Goodman uncovers the surprising origins of the poodle's famous haircut; finds out what makes greyhounds the fastest dogs on the planet; and travels to the Guisachan Estate in the Scottish Highlands to meet hundreds of golden retrievers at the ancestral home of this popular breed. Steve meets the hairiest dog breed of all and reveals how its dreadlocked coat once acted as lightweight armour. Kate investigates the remarkable story of dogs - from their ancient ancestor the grey wolf, through thousands of years as our working companions, to the Victorian creation of the dog breeds we know today.

Kate, Steve and the team of canine experts explore how the huge range of dog breeds differ in their senses and abilities. Does a short nose impede a sense of smell? Do floppy ears mean subdued hearing? And what effect does the shape of a skull have on peripheral vision? The team examines how humans have harnessed these inherent skills and discovers how this has shaped these breeds into the hunters, herders and guard dogs of today. They also see the senses develop in a litter of newborn puppies, and follow Kate's Welsh Sheepdog puppy Teg getting her first lesson in sheep herding. Ruth Goodman is joined by a pembrokeshire welsh corgi as she traces the breed's history to their humble origins as cattle herders. The team also finds out how hunting breeds such as springers, pointers and retrievers evolved with the development of gun technology. Over the centuries dogs have demonstrated that they are highly intelligent animals capable of helping humans with many different tasks. But just how intelligent are they? Can a dog be taught to read? The team finds out when they put three dogs to the test.

This time the team looks at the special relationship between people and dogs. How much of our pets' behaviour and personality is as a result of their nature and how much comes from us? Looking at both ends of the lead, the team delves deep into the psychology of the human/dog relationship. They discover how dogs have evolved to read us better than any other creature on the planet, outperforming even our closest living relative, the chimpanzee. The team explores the UK's top ten breeds, investigating what makes them the most popular pooches. They also take a look at the future of dogs and at emerging crossbreeds, such as the Labradoodle and Cockapoo, that are becoming increasingly popular. Ruth Goodman digs deeper into the history of Greyfriars Bobby, one of the most famous dogs in the world. This loyal dog kept vigil at his master's grave for 14 years. She also visits a pug dog welfare and rescue association celebration to reveal why these lapdogs have their owners wrapped around their little paws and she travels to Swimbridge in Devon, the home of John Russell, the man who created the Jack Russell terrier.