Michael Mosley takes us on extraordinary journey around the human body. Michael puts his body to the test to help you at home understand yours, as he tracks down answers to lots of burning questions, such as; Why do we get creaky joints? What happens when we catch the flu? Can we help our brains stay fit as we age? How do doctors replace a hip? We meet people from around the country with stories to share that shed light on the hidden marvels of our bodies.