Cover-ups, coincidences, and conspiracy theories: where did Covid come from? John Sudworth was the BBC's China correspondent when an unexplained pneumonia started worrying Wuhan doctors in December 2019. Since then, he's been investigating the origin of the virus that would turn into a devastating global pandemic. From the beginning, there have been claims of certainty. Many scientists say the virus that causes Covid came from nature - probably carried from bats to other animals, and then to humans in a Wuhan market. But an alternative possibility - that it leaked from a laboratory - has refused to go away. And other scientists claim there's uncertainty. For them, the mystery of Covid's origin remains unsolved. So, where did Covid come from? For every one of the millions of lives lost, for every long sufferer, for the pain, the isolation, and the incalculable economic cost, the answer matters. It might also help us prevent another - maybe even worse - pandemic. But it's a debate that's become politicised, toxic, and a bit crazy. Presenter: John Sudworth Series Producer: Simon Maybin Editor: Richard Vadon Commissioning Editor: Dan Clarke

The failures in post-war Iraq would have wider consequences for the Western desire to intervene in crises. As first Libya and then Syria slip into violence, how far did Iraq lead to a retreat and were the right lessons learned? Presenter: Gordon Corera Series Producer: John Murphy Producers: Ellie House, Claire Bowes Sound Designer: Eloise Whitmore, Naked Productions Production coordinators: Janet Staples, Brenda Brown Series Editor: Penny Murphy

Have new generations of Iraqis got the freedom they were promised? What is the legacy within Iraq today particularly for a new generation seeking democracy? And how do those directly involved in events reflect on the legacy of war twenty years on? Presenter: Gordon Corera Series Producer: John Murphy Producers: Ellie House, Claire Bowes Sound Designer: Eloise Whitmore, Naked Productions Production coordinators: Janet Staples, Brenda Brown Series Editor: Penny Murphy

The widespread view among the British public that they had been misled about the reasons for war would leave deep scars. What is the legacy of the Iraq war on trust in public life and politics, and what has been the toll on individuals and societies? Presenter: Gordon Corera Series Producer: John Murphy Producers: Ellie House, Claire Bowes Sound Designer: Eloise Whitmore, Naked Productions Production coordinators: Janet Staples, Brenda Brown Series Editor: Penny Murphy

The invasion of Iraq was supposed to be about dealing with security threats but the chaos would turbo-charge extremism both within Iraq and in the UK. How far did Iraq make the threats worse and were warnings ignored? Presenter: Gordon Corera Series Producer: John Murphy Producers: Ellie House, Claire Bowes Sound Designer: Eloise Whitmore, Naked Productions Production coordinators: Janet Staples, Brenda Brown Series Editor: Penny Murphy