How could a deadly epidemic, with the potential to cause a worldwide disaster, strike Wuhan, China—a city of 11 million tech-savvy people—with virtually no details leaking to the world at large? Learn how China has implemented a vast censorship system to maintain an iron grip on the internet usage of its 1.4 billion citizens—a system that has been used to keep the world in the dark for months about a looming danger to every nation on Earth.