Reveals the events behind KURT COBAIN's death as seen through the eyes of Tom Grant, the private investigator that was hired by Courtney Love in 1994 to track down her missing husband Kurt only days before his deceased body was found at their Seattle home. Cobain's death was ruled a suicide by the police (a reported self-inflicted gunshot wound), but doubts have circulated for twenty years as to the legitimacy of this ruling, especially due to the work of Mr. Grant, a former L.A. County Sheriff's detective, who did his own investigation and determined there was significant empirical and circumstantial evidence to conclude that foul play could very well have occurred.
The film develops as a narrative mystery with cinematic re-creations, interviews with key experts and witnesses and the examination of official artifacts from the 1994 case.

Dr Alice Roberts re-traces the greatest ever journey taken by our ancestors. Thousands of years ago one small group of our species, Homo sapiens, crossed out of Africa and into the unknown. Their descendants faced baking deserts, sweat-soaked jungles and frozen wildernesses and risked everything on the vast empty ocean. Within 60,000 years they colonised the whole world... How did they do it? Why do we, their descendants all look so different?

The series highlights the major events which have shaped the Earth's history and allowed life to flourish. Follow Dr Stewart's personal journey to some of the most remote places on the planet. The atmosphere is Earth’s protective layer, cloaking us in a warm, oxygen-rich embrace and shielding us from the cold hostility of space. It acts as a natural greenhouse, keeping the Earth 51 degrees Fahrenheit warmer than it would otherwise be. Yet the atmosphere is also full of contradictions. It’s immensely powerful but at the same time highly sensitive. It’s destructive, yet it shelters us. It was created in part by the planet’s first organisms, and it continues to be essential for life.

Silk is the invertebrates' great invention, used in a range of ways from from the protective stalks of lacewing eggs to the amazing hanging threads of New Zealand's 'glow worms'. Spiders, though, have taken silk-spinning to extremes. The common wolf spider has no web, but the female is a gentle parent, encasing her eggs in silk and carrying the precious bundle wherever she goes. The bolas spider uses a ball of sticky silk soaked in a copy of moth pheromone to lure its prey. Millions of communal spiders live and feed together in a vast, towering web - an arachnophobe's nightmare.

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.