Wuhan, China's economic heartland - and the epicentre of a global pandemic. In 2017, the BBC 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.