With the Doomsday Clock the closest it's ever been to midnight, Jane Corbin investigates the proliferation of nuclear weapons across the globe. She visits Los Alamos, home to the United States’ nuclear weapons development facility and the historic home of Oppenheimer’s Manhattan Project.
In Scotland, she reveals the strategy behind Britain’s nuclear deterrent, and speaks to campaigners in Suffolk fighting against US weapons they fear will be based on UK soil. Jane also discovers how many of the global agreements and safeguards that have constrained the spread of nuclear weapons since the 1970s are breaking down.
This is a story told by the scientists, investigators and diplomats who set the clock and have fought to ensure that the ultimate deterrent has not been used in over 70 years.

In the fourth episode, several women recall their harrowing experiences with one man's heinous attempts at virtual blackmail, aimed at obtaining sensitive sexual material.
A woman tells us: 'I received a message from a man who said: Send me a naked picture or I will kill you'. This young woman was able to add her case to those of other women who were encouraged to denounce and expose the harasser. No one is completely invisible on the Internet.

Frontline and service workers have borne the health consequences of the pandemic, increasing racial and economic disparities. Certain robotic and AI applications are accelerating as the value of human workers is further questioned. Determining the likely areas of job growth and training needs is difficult. Post-secondary education has become more virtual and its costs, more controversial. How can we predict job growth, training needs and the role of education in order to prepare for the work of the future?

To recruit actors for his rehearsals, Nathan opens an acting studio in Los Angeles, teaching 'the Fielder Method', which involves covertly observing and imitating unaware subjects. Feeling insecure about his own performance, Nathan reenacts the class with actors and a fake Nathan as the teacher while the real Nathan plays the role of Thomas, a student. Nathan makes his students immerse themselves in other people's lives while he immerses himself in Thomas's life, even living in Thomas's home.
Nathan returns to Oregon, where his 'son', Adam, is now a teenager. Nathan and Joshua, the actor playing Adam, decide that Adam should lash out due to resentment of his absentee father and develop a drug problem, a situation that mirrors Angela's own past. Adam suffers an overdose and is tended to by emergency responders played by Thomas and another Fielder Method graduate. After he runs away from home, the 15-year-old Adam reverts to a 6-year-old since Nathan plans to relive his son's earlier years.

After losing his drive to continue surfing at Nazaré, Garrett McNamara decides to return to competitive surfing at other big-wave sites. In order to compete in a tournament at California's Mavericks surf site, he must surf there regularly, something that he has done many times in the past. McNamara returns to Mavericks only to suffer a horrific injury on a wave he should have aced.

Former students of Archbishop Keough High School reveal allegations of sexual abuse by Father Joseph Maskell, the chaplain of the school. It details the personal story of 'Jane Doe' (Jean Hargadon Wehner) who claims that Father Maskell took her to see the dead body of Sister Catherine Cesnik in Lansdowne, Maryland.