The Girl You Left Behind is broken into two time periods: the first in 1916 with Sophie Lefevre struggling to keep herself and her family alive in a German-occupied town in France. Her beloved husband Edouard, a French artist who studied under Matisse, is fighting at the Front. When the local Kommandant takes an interest in a painting that Edouard did of his wife, Sophie is forced to make life-altering decisions regarding how much she will do to survive the war and save her husband.
Almost a century later, Liv Halston is a young widow in London, still recovering from the sudden death of her husband four years prior. Facing financial disaster and loneliness, Sophie realizes that one of the few things that give her comfort is the painting her husband bought for her on their honeymoon, titled The Girl You Left Behind. So when the artist's family stakes a claim on the painting, Liv decides she will do anything to hold on to it, and to find the truth about what happened to the painting after it left Sophie's hands. During this time, Liv unexpectedly falls hard for Paul, but soon learns that Paul may be fighting for the wrong side. Liv discovers that she & Sophie have much in common, and decides to fight the impossible fight to keep the painting, while also keeping Sophie's memory untainted.