Gordon Buchanan completes his equatorial journey in south east Asia, where booming economies put increasing pressure on the natural world. Flying over Indonesia’s capital, Jakarta, Gordon discovers this megacity is sinking. In Sumatra, drones help to manage a dangerous conflict between elephants and farmers. In Borneo, which has lost more than a third of its lush forests, Gordon searches for orangutans at night, and he finds that aerial tech offers hope for endangered Siamese crocodiles.