Google X is a secretive laboratory that aims to take over the research and innovation crown once worn by the likes of Bell Labs and DARPA. It’s also about securing the giant technology company’s future in a ruthless world of technological change. We talk to Brad Stone, the first journalist allowed inside the lab. We also explore the history of the Sea Lab project, an attempt to live and work under the seas. And finally we look at the Earth Microbiome Project, an ambitious attempt to map the world's diverse microbial community.