In the final episode, Richard Fortey travels to Madeira to examine what happens to a volcanic island as it nears the end of its life cycle and starts sinking back into the sea. Here, in the island's laurisilva forest, he examines the remains of an ancient forest that once carpeted all of Europe, finds island lizards that live to be four times older than their mainland counterparts, and meets a huge wolf spider. With the help of local divers, he also discovers an unexpectedly rich marine habitat populated by whales, dolphins and unusual deep-sea species that have much to tell us about the changing nature of our seas.