A quarter of British households have a dog. But some people don't just want to own a dog; they want to be one. Secret Life of the Human Pups introduces a previously unseen subculture of ordinary men who lead extraordinary double lives, dressing up in elaborate dog suits that cost thousands of pounds as they strive to become their very own pet. Human puppy play has become a global phenomenon in recent years and there are now an estimated 10,000 'human pups' in the UK alone. But what makes these grown men covet doggy treats, belly rubs and squeaky toys? And why has it risen in popularity? Getting under the skin of this weird and wonderful world, this documentary explores what it takes to become a human pup, the impact it has on friends and loved ones and why, for some people, it has become a way of life.