Ariadna (Laia Costa) discovers that her grandfather has been searching for a long time for the remains of her father, who disappeared in the Civil War. Determined to help him, she travels to Burgos, where they are exhuming a mass grave in which he could be buried. During her stay there, she learns the story of Antoni Benaiges (Enric Auquer), a young teacher from Tarragona who, before the war, was her grandfather’s teacher. Through an innovative pedagogical method Antoni inspired his students and made them a promise: to take them to see the sea.