Five French soldiers are convicted of self-mutilation in order to escape military service during World War I. They are condemned to face near-certain death in the no man’s land between the French and German trench lines. It appears that all of them were killed in a subsequent battle, but Mathilde, the fiancée of one of the soldiers, refuses to give up hope and begins to uncover clues as to what actually took place on the battlefield. She is all the while driven by the constant reminder of what her fiancé had carved into one of the bells of the church near their home, MMM for Manech Aime Mathilde (Manech Loves Mathilde; a pun on the French word aime, which is pronounced like the letter “M”. In the English-language version, this is changed to “Manech’s Marrying Mathilde”).
Along the way, she discovers the brutally corrupt system used by the French government to deal with those who tried to escape the front. She also discovers the stories of the other men who were sentenced to the no man’s land as a punishment. She, with the help of a private investigator, attempts to find out what happened to her fiancé. The story is told both from the point of view of the fiancée in Paris and the French countryside—mostly Brittany—of the 1920s, and through flashbacks to the battlefield.
Eventually, Mathilde finds out her fiancé is alive, but he suffers from amnesia. Seeing Mathilde, Manech seems to be oblivious of her. At this, Mathilde sits on the garden chair silently watching Manech with tears in her eyes and smile on her lips.