For eight years, the freediver Craig Foster has explored the rare wildlife off the coast of South Africa. His daily observations of a wild octopus living in a kelp forest develops into a close bond, across species and separated by millions of years of evolution. The ingenuity and quick wit of the octopus bear witness to a highly developed intelligence. With Roger Horrocks (BBC's 'Blue Planet II') behind the camera, we are brought below the surface of the sea and into another world full of colourful and quirky animals, and witness the wonders and brutality of nature. The encounter with the octopus changes Craig's life forever.