Seventy-five years later, Ariadna (Laia Costa), the granddaughter of one of Benaiges’ former pupils, uncovers the moving and long-forgotten story behind his promise. Her search for the remains of her great-grandfather, one of the many who "disappeared" during the Spanish Civil War, leads her to a mass grave in Burgos. There, she unravels the fate of Benaiges, whose ideals and innovative teaching methods made him a target. The Teacher Who Promised the Sea is a powerful historical drama based on the true story of Antoni Benaiges (1903–1936) and the novel El maestro que prometió el marby Francesc Escribano. In addition to writing the book, Escribano also serves as a producer on the film. Together with director Patricia Font, he presents a poignant story about the pain that still lingers in Spanish society and a tribute to a man who believed in the future of his students and in a promise that lives on despite everything.