In the closing days of World War I Mathilde (Audrey Tautou) receives word that her fiance, Manech (Gaspard Ulliel), has disappeared from the trenches of the Somme. Unwilling to accept that Manech is lost to her forever, Mathilde begins an extraordinary journey to discover the fate of her lover. At each turn, Mathilde encounters another, different, variation of how Manech must have spent his final days...yet Mathilde never gives up and never lets go.