A boy lives with his mother and younger sister. One day, his mother disappears with her lover, leaving the two children alone. António, the older brother, takes care of his sister, Maria da Luz. The little girl is about 10 months old. When she starts walking, their mother reappears with her lover, takes the girl, and leaves the boy behind. António is devastated, as he had been living for several months with a single goal: to protect his sister.