A story based on true events. When Antonio receives a diagnosis that threatens to tear his family apart, his daughter and granddaughter return to Málaga to be with him. There, Lucía, determined to save her grandfather, clings to her faith and makes a promise to the Cautivo: to play music in his footsteps in exchange for her life. Through music, sacrifice, and hope, the granddaughter embarks on a journey that will transform not only her own life, but also that of her entire family.