Not long ago, they were calling each other names and raising fears of a nuclear war. Now, it is feasible they could together win the Nobel Peace Prize - if they can reach a deal. The mooted meeting between America’s Donald Trump and North Korea’s Kim Jong Un could go wrong in many ways. Mr Trump has already talked of walking out. But in a spirit of optimism, this week’s Inquiry hears from those who have brokered some of the world’s most unlikely pacts for advice on how to strike the deal of a lifetime. With Helena Merriman.

(Photo: President Trump, Credit: Zach Gibson/Getty Images; Photo: Kim Jong Un, Credit: Korea Summit Press Pool/Getty Images)