We travel to Silicon Valley where Astro Teller welcomes us inside X, Google's secretive innovation laboratory, to explain how one of the most powerful companies on earth is building the future. X is working on everything from creating new antibiotics to restoring internet connectivity after natural disasters. And they're not alone. Tech companies are increasingly involved in building infrastructure, and even playing the role of government. But what kind of power does this give them? And what can we do to rein it in?