Ewan and Charley swap their e-Harley Davidsons for plane first and follow it up with a journey by ship to Panama. McGregor's bike needs some repairs and will be fixed by the time they reach Costa Rica. The ship they travel in with the bikes looks like a beaten-down vessel that raises genuine concerns about making the journey in one piece. The boat crew looks sharp and proactive while trying to make the show crew's journey as comfortable and safe as possible. The episode also introduces Nuqui, one of the wettest regions in the world where the ship quickly makes a pitstop to fuel up on essential supplies.

Space colonization is no longer the fodder of science fiction, it is becoming a reality. Examine the efforts underway to establish a human colony on Mars, including how they plan to grow food, recycle wastewater and introduce greenhouse gases to revive the red planet and make it more habitable for humans. Cutting-edge computer graphics are used to bring the universe down to earth to show what life would be like on Mars, and to imagine what kind of life forms might evolve in alien atmospheres.

In this episode, Helen seeks out the colours that turned planet Earth multicoloured. To investigate the essence of sunlight Helen travels to California to visit the largest solar telescope in the world. She discovers how the most vivid blue is formed from sulfur atoms deep within the Earth's crust and why the presence of red ochre is a key sign of life. In gold, she discovers why this most precious of metals shouldn't even exist on the surface of the planet and in white, Helen travels to one of the hottest places on Earth to explore the role salt and water played in shaping planet Earth.

Earth is the most colourful place we know of. But the colours we see are far more complex and fascinating than they appear. In this series, Dr Helen Czerski uncovers what colour is, how it works, and how it has written the story of our planet - from the colours that transformed a dull ball of rock into a vivid jewel to the colours that life has used to survive and thrive". But the story doesn't end there - there are also the colours that we can't see, the ones that lie beyond the rainbow. Each one has a fascinating story to tell. Early Earth was a canvas for the vast new palette of the colours of life, with the diversity of human skin tones telling the story of how humanity spread and ultimately conquered the planet. Dr Helen Czerski explores the true masters of colour - which are often the smallest and most elusive - travelling to the mountains of Tennessee to witness the colourful mating display of fireflies, and revealing the marine creatures that can change the colour of their skin in order to hide from the world.

What If we could talk to animals? For as long as we've shared our lives with pets, we've been seeking better ways to communicate with them. In Washington state, Alexis Devine and her sheepadoodle Bunny think they've found a way of making communication a reality. Alexis went further than most, with a set of communication buttons, each programmed with a pre-recorded word to help humans and animals speak the same language. She has 90 buttons with which to express herself and even seems to combine them into simple sentences. Bunny is paving the way in pet communication.
The undisputed masters of verbal communication are our pet parrots. They have mastered the art of vocal expression. Some parrots have even learned to fool devices designed to recognize human voices.

The very heart of Africa is covered in dense tropical rainforest. The animals that live here find the most ingenious ways to carve out their space in a claustrophobic landscape. Danger lurks in every shadow, but some animals thrive here, from honey-stealing chimps to birds with a lineage as old as the dinosaurs, thundering elephants and kick-boxing frogs. Here in the Congo, no matter how tough the competition, you must stand up and fight for yourself and your patch.