Horizon investigates the idea that the best way to lose weight successfully is a personalised approach, diets tailored to our individual biology and psychology. In a groundbreaking experiment, Dr Chris van Tulleken and Tanya Byron join a team of experts to put 75 overweight volunteers on diets designed to tackle the specific reasons why they eat too much. The volunteers are put through a series of tests at a residential clinic to understand how their genes, hormones and psychology influence their eating behaviour. They are then put on the diets the experts believe are best suited to them. Can science succeed where other diets have failed?

It's Valentine's Day and Maddi steps out on her first ever date with a romantic man. Kelvin works with a relationship specialist and puts his dating skills to the test. Michael is overwhelmed when he meets the woman of his dreams.

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.

We are familiar with images of the hearings at the Nuremberg trials. But to this day, no one has taken us into the cells and minds of the accused. Leon Goldensohn, a 34-year-old American Jewish psychiatrist, spent six months visiting the 4 main Nazi war criminals.
Based on these unique and recently uncovered documents and reconstitutions of the main events, this film discloses for the first time the personal thoughts of the Nazis: Hermann Goering, Rudolf Hess, Hans Franck and Julius Streicher. These interviews raise serious questions concerning the psychic mechanisms and mysteries that set off acts of barbarity.

Your brain is like a hungry sponge. It's constantly absorbing information. It thrives when stimulated. Between smartphones and books, and movies, and friends and family, thousands of sensations are constantly going into our heads. But what if it all got cut off?. Imagine being confined to a 10-by-10-foot room in complete isolation. No timekeeping devices, no phones, no books, nothing to write on, no windows. Psychologists say that fewer than three days in a room like this can lead to brain damage. I will be staying in this room for three days.
Michael explores the effects of isolation on the human mind by subjecting himself to a very interesting experiment.

Mark has never had a girlfriend, but he wants love more than anything. Maddi and Mark are going on their second date at the Australian Museum. Olivia has had 'a bazillion' unrequited loves but is not ready to give up. Maddi dates a new man who impresses her with his musical talent.