Michael Mosley heads to Snowdonia, on a mission to demonstrate what stress does inside all our bodies.

In Durham, we discover that we all possess an incredible hidden ability: Jayne shows us how she learned to see again by using echolocation. Michael tackles that burning question often on all of our minds: what is in our farts?

And in Middlesex, Claire is admitted for a pioneering hip replacement that she hopes will finally make her life pain free.

In the first episode, Michael Mosley heads to Dundee to meet tremors sufferer Thomas who is about to undergo pioneering brain surgery. In Southampton, Allen finds out if his experimental cancer treatment has been a success and Michael takes the plunge to reveal the health benefits and risks of cold water swimming, as well as a state-of-the-art test that could help predict heart problems years in advance.