Squeezed between South East Asia's two most formidable geographical barriers, the Annamite mountains and the Mekong river, lies Khammouane - a rugged karst landscape, honeycombed with countless caves. These caves were formed by water flowing down towards the Mekong. Unlike life above ground that is subject to continual change, the different seasons or day and night, cave environments are constant. It's a world of total darkness, stable temperatures and high humidity. Many creatures retreated into the caves millennia ago and now are perfectly adapted to this environment. The cave inhabitants are divided into three distinct groups. There are the part time residents such as bats that use the caves to roost. Then there are the permanent residents that are born in the cave system and never leave; the crustaceans, cockroaches, the giant centipedes and spiders. Some of these creatures have lost their pigmentation and eyesight as they have evolved in the darkness. Finally, there are the cave visitors. These creatures usually come here to hunt; the snakes, the geckos and the frogs. The lives of the species in each zone of the cave are interlinked. This unique cave system is also home to the largest spider on earth, the recently discovered giant huntsman. This hunter has a leg span of 30cm. The huntsman competes with giant centipedes, snakes, bent toed geckos and other predators that prey on cave inhabitants and any creatures that might wander in. However, the deepest corners of the cave have the most peculiar creatures: purple crustaceans with long spindly legs feel their way around. In a pitch-black world they rely on very different ways to survive. Back on the surface, red-shanked doucs live in the jungles that cloak the karst hills above the caves. They are the most colourful of all primates, and welcoming babies into the world just in time for the fruiting season. We immerse ourselves in troop life, daily routines, infant care and the hierarchy. We follow a baby douc exploring its new world.