A plush country house is fixed with surveillance cameras while a group of unwitting test subjects are first exposed to youthful memories to test if it can improve their health. Dr Mosley takes them on this nostalgia trip with the help of neuroscientist Dr Jack Lewis and psychologist Anna Machin to determine how reliable memories really are.

Michael Mosley and a team of experts place human behaviour under the microscope. In the final episode, Michael and scientists Dr Jack Lewis and Dr Jennifer Wild explore the biology of fear and anxiety in the modern world. Fear is one of our most basic human emotions. In the past, it kept us from being eaten by a wild animal. But today, that isn't so much of a threat and yet we live in a state of anxiety - it's becoming unhealthy.