John Humphrys returns to South Wales to discover more about the devastating Nazi bombing campaign and how it affected those who experienced it. He sees the reconnaissance maps the Germans used to identify key bombing targets. He also takes to the air, to follow the direct flight path of the Luftwaffe bombers as they attacked Cardiff and Swansea. Back on the ground, John meets survivors of the bombings, including Elaine Kidwell from Swansea, who describes the Blitz on the city as hell. He also visits locations where the bombs hit, including the site of Hollyman's Bakery, the setting for the worst single atrocity in Cardiff. This is a personal story for John, who was born in 1943 and who remembers playing amongst the rubble of the bombsites in Splott near Cardiff docks.