In this film, Professor Iain Stewart shows how plants are the silent power that has shaped the Earth. They harnessed light from the sun and created our life-giving atmosphere; they formed the fertile soil; they sculpted the planet itself; and drove the evolution of animal life. Iain journeys to some of the most striking locations on Earth to see what modern plants tell us about their pioneering ancestors. He carries out experiments demonstrating the power of plants to transform their surroundings. And using state-of-the-art photography, Iain gazes into the inner world of plants to unlock their secrets.