It was a story that shocked the world. In August 2020, Russia’s opposition leader Alexei Navalny was taken ill during a flight to Moscow. He was suspected of being poisoned with the banned chemical weapon Novichok, applied to his underwear. This remarkable Putin and Navalny documentary on BBC Select tries to unravel the bizarre case. Was Putin involved in the plot and if so, why did he want this man dead? WATCH