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.

If you had less than one second to make a life-or-death decision to shoot a man who might be armed with a lethal weapon, what would you do? Would the ethnicity of the man affect your decision? Are you sure? The outcome – whatever your race – will surprise you. Brain imaging studies are showing that negative cultural stereotypes hijack everyone’s subconscious decision-making. But some science says we can overcome bigotry through exposure, self-awareness and flexible social networks… and, most controversially of all, ultra-violent video games!

In the second episode, Nathan develops a rehearsal for Angela, a woman considering motherhood. Nathan hires child actors to simulate adopting and caring for a baby and sets her up in a rented farmhouse in rural Oregon. Due to Oregon child protection laws, Nathan's team must covertly switch out the baby every four hours and replace it with a robot baby at night. Seeking a simulated husband, Angela dates Robbin, a numerology-obsessed man who wants to have sex with Angela despite her devout Christian beliefs against premarital sex. When Robbin quits the project due to the robot baby's incessant crying, Nathan inserts himself into the experiment as Angela's non-romantic co-parent.

Nathan and Angela accelerate their parenting rehearsal with three-year-old, then six-year-old actors portraying their fake son, 'Adam'. Angela refuses to participate in Halloween due to her belief in Satanic conspiracies.
Nathan balances parenting duties with a rehearsal for Patrick, a man who wants to confront his brother over their late grandfather's will, which bans Patrick from inheriting money if he is dating a 'gold digger'. The rehearsal occurs in a replica Raising Cane's restaurant in a warehouse next to the relocated Alligator Lounge. To introduce real emotions to the rehearsal, Nathan stages a scenario to convince Patrick that he could inherit buried gold from the grandfather of Isaac, the actor who plays Patrick's brother. After Patrick has an emotional breakthrough during a rehearsal, he leaves the production and never returns. Nathan narrates that he is envious that self-deception is easy for some people as he ponders his fake family.

Episode three explores the mind of one of the most fanatical of all Nazis and the insight that gives into the psychology of dictatorship. Hess is brought to Nuremberg from the UK where he had flown 4 years earlier much to the bemusement of the British. Overy explains that they must have quickly realised he was not normal. In the intervening time Hess’s mental state has further deteriorated and when interviewed by Chief Interrogator Colonel John Amen proclaims amnesia. Chief Interpreter Richard Sonnenfeldt explains that they brought in Göring to confront Hess but that he too failed to make an impression.
Psychopathologist Prof. Edgar Jones proposes Hess’s behaviour patterns may be his way of escaping reality as he is forced to face the extent of the atrocities and choose between accepting his part of the blame or forsaking his Führer. However, as history Professor Robert Gellatel explains it is difficult to construct a case against Hess as he was imprisoned in England when the worst of the atrocities were carried out so British Prosecutor Mervyn Griffith-Jones must argue a conspiracy charge linking the pre-1939 persecutions to the post-1939 atrocities and a crimes against peace charge proving the flight to Scotland was merely a ruse.

Moral psychology isn't always an easy thing to study. Experiments that actually puts people in what feels like a real scenario may get realistic results, but researchers must always balance the benefits of what we could learn with the safety and well-being of the people they study. Often what we learn from moral psychology experiments doesn't make humans look good.
We are imperfect creatures. But the more we learn about why and how we make the moral choices that we do, the better we'll be able to tackle difficult questions in the future.