Celebrated actors explore their grandparents' extraordinary wartime stories. Keira Knightley unearths a deeply moving story of resilience and love concerning her grandparents Mac and Jan MacDonald. Her grandfather Mac braved the bombs during the Blitz to make sure he wasn't late for a date with Jan. But their blossoming romance was hugely challenged by the war. Mac was a sonar operator with the Royal Navy. Keira discovers how her grandfather and the crew of HMS Wolverine rescued hundreds of Irish Guards from a sinking ship in under 20 minutes. Keira meets a man whose very existence is inextricably linked to her grandfather, as his own grandfather was one of those men rescued. Keira reveals how millions of women, including her grandmother Jan, volunteered to bolster Britain's war effort. In Scotland, retracing her grandmother's footsteps, Keira discovers how Jan worked in a military hospital and then played a vital and secret role assisting the US Army during the D-Day landings. Keira also tries to comprehend how both her grandparents coped with the news that their younger brothers were reported missing in action. There is also an epic story of escape from a prisoner of war camp and a tale of tragic death. My Grandparents' War - Keira Knightley - Thursday at 9.00pm on Channel 4.