O ne day in November 1941, Catherine Dior went to buy a radio in Cannes. The purchase was consequential: two years into World War II, France had fallen under German occupation. General Charles de Gaulle, a leader of the Resistance and future French president, was known to broadcast speeches from London, where he lived in exile. Owning a radio meant being able to listen to his addresses – and more generally to Radio Londres , a station operated from the BBC by members of the Resistance to their supporters in occupied France. In that radio shop, Catherine met Hervé des...