Jungles provide the richest habitats on the planet - mysterious worlds of high drama where extraordinary animals attempt to survive in the most competitive place on earth. Flooded forests are home to caiman-hunting jaguars and strange dolphins that swim amongst the tree tops, while in the dense underworld, ninja frogs fight off wasps and flying dragons soar between trees. Acrobatic indri leap through the forests of Madagascar, while the jungle night conceals strange fungi and glow-in-the-dark creatures never filmed before.

Professor Richard Fortey delves into the fascinating and normally-hidden kingdom of fungi. From their spectacular birth, through their secretive underground life to their final explosive death, Richard reveals a remarkable world that few of us understand or even realise exists - yet all life on Earth depends on it. In a specially-built mushroom lab, with the help of mycologist Dr Patrick Hickey and some state-of-the-art technology, Richard brings to life the secret world of mushrooms as never seen before and reveals the spectacular abilities of fungi to break down waste and sustain new plant life, keeping our planet alive. Beyond the lab, Richard travels across Britain and beyond to show us the biggest, fastest and most deadly organisms on the planet - all of them fungi. He reveals their almost magical powers that have world-changing potential - opening up new frontiers in science, medicine and technology.

Bladderwort utricularia is a pond-dweller that is among the fastest known, its traps snapping shut in less than a millisecond. As the seasons change, David demonstrates how plants operate on a different time scale to us; how they modify their lives according to the time of year. We discover insects’ hidden links with plants, both as pests and pollinators. UV-sensitive 3D cameras reveal the invisible alter-ego of plants and their flowers’ mesmerizing patterns; a parallel-dimension of strange colours and stunning patterns through which plants communicate with them. With the aid of visual effects, David steps among the swirling vortices of plant scent; communication signals with which plants are inextricably plugged in to the natural world. And using a tuning fork, he demonstrates how plants and insects can even communicate with music. As autumn envelopes the Gardens, fungi reveal themselves not as the enemies of plants but their vital allies. In Kew’s atmospheric Fungarium, David discovers a specimen that has the power of mind control and another that lives underground where it has grown to be so big it can be counted as the largest single organism on the planet. It is 6 times bigger than Kew Gardens itself.

Ron Mann investigates the miraculous, near-secret world of fungi. Visionaries Gary Lincoff and Larry Evans lead us on a hunt for the wild mushroom and the deeper cultural experiences attached to the mysterious fungi. The oldest and largest living organisms recorded on Earth are both fungi. And their use by a new, maverick breed of scientists and thinkers has proven vital in the cleansing of sites despoiled by toxins and as a "clean" pesticide, among many other environmentally friendly applications. Combining material filmed at the Telluride Mushroom Fest with animation and archival footage, along with a neo-psychedelic soundtrack by The Flaming Lips, this film opens the doors to perception, taking the audience on an extraordinary trip where the fungi might well guide humanity to a saner, safer place.

Jungles cover roughly three per cent of our planet yet contain 50 per cent of the world's species. High-definition cameras enable unprecedented views of animals living on the dark jungle floor. In the Ngogo forest the largest chimpanzee group in the world defends its territory from neighbouring groups. Other jungle specialists include parasitic fungi which infiltrate an insect host, feed on it, and then burst out of its body.

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.