This episode explores the palaeogeography of Earth over millions of years, and its impact on the development of life on the planet. Tyson starts by explaining that the lignin-rich trees evolved in the Carboniferous era about 300 million ago, then explains on the nature of plate tectonics that would shape the landmasses of the world and the asteroid impact that initiated the Cretaceous–Paleogene extinction event, leaving small mammals as the dominate species on earth. Earth's landmasses are expected to change in the future and postulates what may be the next great extinction event.

This is the story of three maps, three 'visions' of London over three centuries. The Morgan Map of 1682 was the first to show the whole of the City of London after the Great Fire of London. In 1746 John Rocque produced at the time the most detailed map ever made of London. Like Morgan's, Rocque's map is all neo-Classical beauty and clinical precision, but the London it represented had become the opposite. In engravings of the time, such as Night, the artist William Hogarth shows a city boiling with vice and corruption. Stephen Walter's contemporary image, The Island, plays with notions of cartographic order and respectability. His extraordinary London map looks at first glance to be just as precise and ordered as his hero Rocque's but, looking closer, it includes 21st century markings such as 'favourite kebab vans' and sites of 'personal heartbreak'.

This episode covers the nature of how life may have developed on Earth and the possibility of life on other planets. Tyson begins by explaining how the human development of writing systems enabled the transfer of information through generations, describing how Princess Enheduanna ca. 2280 BCE would be one of the first to sign her name to her works, and how Gilgamesh collected stories, including that of Utnapishtim documenting a great flood comparable to the story of Noah's Ark. Tyson explains how DNA similarly records information to propagate life, and postulates theories of how DNA originated on Earth, including evolution from a shallow tide pool, or from the ejecta of meteor collisions from other planets. In the latter case, Tyson explains how comparing the composition of the Nakhla meteorite in 1911 to results collected by the Viking program demonstrated that material from Mars could transit to Earth, and the ability of some microbes to survive the harsh conditions of space. With the motions of solar systems through the galaxy over billions of years, life could conceivably propagate from planet to planet in the same manner. Tyson then moves on to consider if life on other planets could exist. He explains how Project Diana performed in the 1960s showed that radio waves are able to travel in space, and that all of humanity's broadcast signals continue to radiate into space from our planet. Tyson notes that projects have since looked for similar signals potentially emanating from other solar systems. Tyson then explains that the development and lifespan of extraterrestrial civilizations must be considered for such detection to be realized. He notes that civilizations can be wiped out by cosmic events like supernovae, natural disasters such as the Toba disaster, or even self-destruct through war or other means, making probability estimates difficult. Tyson describes how elliptical galaxies, in which some of the oldest red dwarf stars exist, would offer the best chance of finding established civilizations. Tyson concludes that human intelligence properly applied should allow our species to avoid such disasters and enable us to migrate beyond the Earth before the Sun's eventual transformation into a red giant.

D-Day: As It Happens is a 24-hour history event to be broadcast across TV, web, mobile devices and social media, telling the story of this pivotal event in 20th-century history in a completely new way. Using newly-analysed archive footage, viewers can track the progress of seven people who were there on the day, each of them a real participant in the 1944 invasion. And they can do so moment by moment in real time, encountering the twists and turns of the fighting at the same time as the D-Day seven did, and learning their fate as the action unfolds in parallel with the present, Narrated by Peter Snow, with Channel 4 presenter and former marine Arthur Williams, and experts including former British Army officer Colonel Tim Collins and front-line journalist Lorna Ward. The second programme reveals what happened to the seven real people the event is following in real time, and also rounds up the events of D-Day.

Tyson describes the discovery of cosmic rays by Victor Hess through high-altitude balloon trips. Swiss Astronomer Fritz Zwicky, in studying supernovae, postulated that these cosmic rays originated from these events instead of electromagnetic radiation. Also tells how Vera Rubin observed that the rotation of stars at the edges of observable galaxies did not follow expected rotational behavior leading to consider the existence of dark matter. This further led to the discovery of dark energy to account for the increasing rate of expansion of the universe. Tyson then describes the interstellar travel of the two Voyager probes. Tyson tells the Carl Sagan's role in the Voyager program, including creating the Voyager Golden Record to encapsulate humanity and Earth's position in the universe. Tyson concludes the series by emphasizing Sagan's message on the human condition in the vastness of the cosmos, and to encourage viewers to continue to explore and discover what else the universe has to offer.

Professor Brian Cox takes on the story of the force that sculpts the entire universe - gravity. Gravity seems so familiar, and yet it is one of the strangest and most surprising forces in the universe. Starting with a zero gravity flight, Brian experiences the feeling of total weightlessness, and considers how much of an effect gravity has had on the world around us. But gravity also acts over much greater distances. It is the great orchestrator of the cosmos. It dictates our orbit around the sun, our relationship with the other planets in our solar system, and even the way in which our solar system orbits our galaxy. Yet the paradox of gravity is that it is actually a relatively weak force. Brian takes a face distorting trip in a centrifuge to explain how it is that gravity achieves its great power, before looking at the role it plays in one of the most extraordinary phenomena in the universe - a neutron star. Although it is just a few kilometres across, it is so dense that its gravity is 100, 000 million times as strong as on Earth. Over the centuries our quest to understand gravity has allowed us to understand some of the true wonders of the universe, and Brian reveals that it is scientists' continuing search for answers that inspires his own sense of wonder.