Helen Conroy is happily married with two children and a husband she adores when war is declared. The blitz leaves her homeless, so she returns to her father's house on the Dorset coast, but she is shattered when her husband asks for a divorce.
Then, in September 1942, US troops arrive in Southern England bringing hope and joy along with their cigarettes and chewing gum. These young men will be part of the greatest military invasion the world has ever seen, so Brits and GIs alike live and love for the moment.
Captain Simon Johnson, a US military intelligence agent, is billeted with the Conroys, falling deeply in love with Helen, but this leads to explosive consequences.