Barcelona, Spain, in the late sixties. Eugenio, a young jeweler who has fallen in love with Conchita, a singer, to the point of learning to play the guitar to accompany her in her performances, will first have to learn to overcome his stage fright.

In a remote 1920s village, children live in fear of SACKMAN, a terrifying entity summoned to punish those who misbehave. One boy, abused by his mother, calls the creature against her, unleashing a night of horror and confrontation. Amid shadows and eerie whistles, the limits of morality are tested—and one question remains: who truly has the right to deliver justice?