It is time to see if personalised dieting will work in normal life. The volunteers have been given one of three diets to follow - based on their genes, their hormones and their psychology. But now they are back at home, trying to stick to their personalised diets with all the stresses and temptations of real life. Dr Chris van Tulleken and Professor Tanya Byron discover how our genetic makeup can make temptation difficult to resist, how understanding the brain reveals what makes us comfort eat and what science can tell us about why we make disastrous food choices.

The five directors, John Ford, William Wyler, John Huston, Frank Capra, and George Stevens, return to Hollywood after the war but are forever haunted by what they saw. Ford goes on a drinking bender after filming the carnage at D-Day. Stevens is wholly unprepared for the horrors of Dachau and realizes he is not there to film propaganda but to capture evidence of crimes against humanity. Wyler, who lost his hearing during the war, fears his career is over. Huston chronicles soldiers suffering from postraumatic stress disorder in the film Let There Be Light, only to have it suppressed by the U.S. government.

The third episode looks at anxiety and explores why it is so common. It talks to neuroscientists who explain the physiological and evolutionary basis of anxiety. Although it can help animals escape predators, anxiety can cause serious problems for human beings. It talks to sufferers of anxiety and examines the different types of anxiety people can feel. It also looks at how social media can cause anxiety.

Championed by both therapists and ravers, ecstasy stands out as the first psychedelic likely to become legalized, thanks to passionate advocates.
The episode about 3,4-Methylenedioxymethamphetamine (MDMA), is focused on Multidisciplinary Association for Psychedelic Studies (MAPS) clinical trials treating Post-traumatic stress disorder (PTSD).