The photograph of Alexander Litvinenko on his deathbed in November 2006, poisoned by polonium, caused shockwaves around the world. But how did it come to that? And why are the lessons he provided important now, twenty years on? We are honoured that Alexander's widow Marina Litvinenko brings us answers as she shares her compelling new memoir, A Life in Fragments. Hear the inspirational personal story of how two people got caught up in a struggle against Putin's regime – and the pressures still faced by Putin's critics. 

In conversation with Sian Kevill.