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.