La douleur is set in World War I, when at the age of thirty-five Thérèse Delombre is left a widow after the death of her military captain husband in the village of Althen-des-Paluds, where André de Richaud lived and is buried. The locals have accepted her as she shows humility and lack of haughtiness, but trouble is to come when three German prisoners are lodged in the town. At first they assimilate easily and readily learn the foreign language.
But Thérèse is painfully sexually frustrated, as is the German prisoner Otto, and inevitably the two come together. And equally inevitably there are a number of problems which stem from the relationship: Thérèse falls in love with the ten-years-younger Otto, who can see that she will quickly age and has no plans for their future; with much jealousy and shame, the new Catholic convert Georget hates the German interloper: 'is it a sin to refuse to be kissed [goodnight] by a Kraut?', he asks at confession; and of course the relationship is discovered by the locals, who now view Thérèse with very different eyes.
As, ironically, The Merry Widow is played in the village, the German prisoners are now seen as unwelcome, and Otto has to confess he is leaving Thérèse. This is a little before the distraught Thérèse learns that she is pregnant, and a few months later the prisoners leave. Thérèse has thought of suicide, but an accident makes that task unnecessary. The innocent Georget will be able to be welcomed into the Catholic fold as an orphan.