Singer Alfie Boe discovers how his grandfather helped protect the nation during the war as a member of the Home Guard immortalised in Dads Army. He takes to the sea to find out how volunteers patrolled the country's shores and hears how fishermen from his home town not only helped feed a hungry nation, but were key to a daring beach rescue on the beaches of Dunkirk. Overwhelmed by the sacrifices made to keep wartime Britain safe, he meets a 97-year-old fisherman who risked his life to defend the British coastline.