Chris Packham sheds light on the magical underground world of three iconic British creatures - badgers, water voles and rabbits, in one of the biggest natural history experiments ever undertaken. In specially created full-scale replica burrows, it's summer. All the burrowers face a new challenge - they must leave their home and learn to survive outside. Will the orphan badger cubs be independent enough to survive in the wild? How will the young water voles cope on their own - just 3 weeks after they were born? The rabbit warren is full to bursting and, never seen before, two female rabbits are sharing a nest with 17 baby rabbits. How do the rabbits use hierarchy to create order? And for the first time, Chris and his team of experts use 3D mapping to reveal how a wild rabbit warren expands and evolves over time.