Fueled by a ruthless and maniacal ambition to conquer Central Japan, Nobunaga has destroyed many enemies who have underestimated him. His vicious military campaigns to weaken the powerful Buddhist institutions have turned large swathes of the population against him. As Nobunaga's cruelty intensifies, some generals begin to question his command, leading to a betrayal that alters the political landscape forever.

Episode 4 rounds everything out while simultaneously focusing on his career and the next steps. After a performance tribute to Jamal, Ed and Cherry get good news and reflect on a turbulent year.

The story of Tilikum, a captive killer whale that has taken the lives of several people , including a top killer whale trainer, underscores the consequences of keeping these powerful animals in captivity, the problems within the sea-park industry, the man's relationship to nature, and how little has been learned about these highly intelligent and sentient mammals.
Tilikum was captured in the northern Atlantic Ocean in 1983 and taken to Sealand of the Pacific, a now-shuttered park near Victoria, British Columbia. Former Sealand trainers interviewed in 'Blackfish' say the park’s female killer whales would aggressively gang up on Tilikum, particularly when they were confined in a 20-foot-by- 30-foot pool overnight.

In the last episode, despite disturbing revelations of wrongdoing at Three Mile Island before and after the accident, the utility fights to bring the plant back online. Its Unit 1 had its license temporarily suspended following the incident at Unit 2. Although the citizens of the three counties surrounding the site voted by an overwhelming margin to retire Unit 1 permanently in a non-binding resolution in 1982, it was permitted to resume operations in 1985 following a 4–1 vote by the Nuclear Regulatory Commission.
In 2017, it was announced that operations would cease by 2019 due to financial pressure from cheap natural gas, unless lawmakers stepped in to keep it open. Unit 1 shut down on September 20, 2019.
Billed as the worst nuclear incident in U.S. history, what’s particularly scary here is how close Three Mile Island incident came to becoming a national disaster. Without giving away the whole story, cost-cutting 'solutions' almost cause a catastrophic disaster.

From the frozen poles to the searing deserts, this episode shows how animals have come up with strategies to survive the uneven amounts of sunlight that fall on our planet over the course of a year. The exception is on the equator, where the duration of day and night remain the same throughout the year. Here, this guaranteed sunlight drives the great diversity of life in the tropical jungles.

Weather controls the distribution of freshwater on Earth. David Attenborough narrates how this uneven distribution has given rise to an incredible diversity of species and habits, from the driest desert to the lushest tropical rainforest. Featuring a colony of ants banding together into a raft every time its home in the Amazon floods, a rain frog that manages to eke out an existence in one of the world's driest habitats on Earth, and the last wild camels that survive the Gobi Desert's bitter winters by eating snow that blows in from Siberia.