Fourth episode examines how plants either share environments harmoniously or compete for dominance within them. Attenborough highlights the 1987 hurricane and the devastation it caused. However, for some species, it was that opportunity for which they had lain dormant for many years. The space left by uprooted trees is soon filled by others who move relatively swiftly towards the light. The oak is one of the strongest and longest-lived, and other, lesser plants nearby must wait until the spring to flourish before the light above is extinguished by leaves. Tropical forests are green throughout the year, so brute force is needed for a successful climb to the top of the canopy: the rattan is an example that has the longest stem of any plant. As its name suggests, the strangler fig 'throttles' its host by growing around it and cutting off essential water and light. Some can take advantage of a fallen tree by setting down roots on the now horizontal trunk and getting nutriment from the surrounding moss and the fungi on the dead bark. The mountain ash (eucalyptus regnans) grows so tall, that regeneration becomes a considerable problem. It is easily flammable, so its solution is to shed its seeds during a forest fire and sacrifice itself. It therefore relies on the periodic near-destruction of its surroundings in order to survive. Attenborough observes that catastrophes such as fire and drought, while initially detrimental to wildlife, eventually allow for deserted habitats to be reborn.

The Great Pyramid of Giza's construction is still shrouded in mystery, despite it being the only survivor among the Seven Wonders of the Ancient World. In Building the Great Pyramid, travel back 4,500 years with the BBC as they re-create the circumstances under which it may have been built, as well as the daily life of the population at that time. Expert archaeologists, Egyptologists, and scholars share their latest theories on what may have happened. The film combines dramatic reconstruction, location shooting and state-of-the-art CGI computer effects. Directed and written by Jonathan Stamp.

Having learned that Vorenus' children are alive, Pullo sets off to find him in Gaul where he is again a serving soldier in Mark Antony's army. He had hoped to arrive before Octavian and Antony's armies meet in battle. Too late however, he is forced to find what is left of Antony's army in the mountains. He finds Vorenus alive and well, if somewhat battle worn, and they set off to find the children.
The victorious Octavian plans his return to Rome. In Western Turkey, Brutus and Cassius amass their own army, now 19 Legions strong.

Jeffrey Epstein brokers a plea deal that's unprecedented in its leniency, and a survivor opens up about the horrors she endured on his private island. Epstein Jeffrey shared his island with a lot of powerful and well-known figures, both politically and financially.

Bill Gates is on a mission. He needs to unlock the mysteries of the PDP-10 computer. But the adults won't share the source code with 13-year-old Bill. So he enlists his older friend Paul Allen. Together they boldly go where no one has gone before. If they find the source code, Bill and Paul will finally be able to master the computer.
The connections that shaped Bill Gates' life come into focus, including a childhood friendship and his unique bond with Microsoft co-founder Paul Allen.

Everything that lives on land, animal or plant, depends on fresh water. Yet only part of it is within reach: Much of the planet's fresh water, is locked away, almost two-thirds of it lies frozen around the poles. Even away from the poles, much of the land's fresh water freezes each winter. The need for fresh water is as strong as ever. However, the supply is becoming increasingly unpredictable and uncertain for all manner of species. We are not alone in our need for water, but we have the ability to ensure the fresh waters of the world do flow, and we alone can determine how they are shared.