In the culmination of this 1,000km scientific expedition aboard the Alucia, Liz Bonnin and the team of experts journey south to visit the oldest islands in the Galapagos to see first-hand the impact that humans have had on this pristine wilderness. On the island of Isabela, Liz descends into a spectacular vertical lava cave. Deep inside, she discovers how this hidden world might even provide an answer to how it could be possible to inhabit other planets. On Santa Cruz, Liz comes face to face with the effects of man as she explores the scalesia forests and meets scientists who are tracking the invasive species spreading throughout the islands. She also checks in on a giant tortoise population whose ancient migration pathways have come under threat. Finally, Liz dives into the deep blue waters to witness the birth of a brand new island. Coming full circle, Liz and the team are able to reflect on the importance of their missions which will help to protect the Galapagos Islands.