Wuhan, China's economic heartland - and the epicentre of a global pandemic. Three years ago we set out to follow the fortunes of two companies as they fought to establish themselves in the city's Optics Valley, a dedicated zone for new technology enterprises. This is the story of some of the people who live and work in this city. And the story of Wuhan before and after the arrival of the coronavirus that would change all of our lives. On average, 70 start-ups are registered every day in Wuhan, and robotics company CEO Xu Jishui and software entrepreneur Huang Tiesen are hoping they can break into this major new technology centre. But they face mounting challenges.