After Japan's attack on Pearl Harbor in 1941, Hitler declared war on the U.S., unleashing U-boat submarines to attack American ships. Suddenly, the waves outside Louisa June's farm are swarming with hidden enemies. Her mama has always swum in a sea of melancholy, but now she really needs Louisa June to find moments of inspiration to buoy her. Like sunshine-yellow daffodils, good books, or news accounts of daring rescues of torpedoed passengers. Determined to help her Mama and aching to combat Nazis herself, Louisa June turns to her friend Emmett and Cousin Belle, who has her own war stories to share. In the end, Louisa June learns the greatest lifeline is love.