Did China hide crucial information about Covid-19 from the world? What began with a handful of mystery pneumonia cases in Wuhan late last year has now left more than half a million dead worldwide. Beijing says it has been open and transparent throughout, but former BBC China Editor Carrie Gracie investigates how it delayed reporting the initial outbreak and evidence that Covid-19 could be spread by people. It also silenced doctors who tried to speak out. Panorama also hears from one high-level insider who believes the animal market at the centre of the Wuhan outbreak should have been treated as a 'crime scene' and from experts who warn that this crisis may be a 'dress rehearsal' for an even more deadly pandemic in the future.