The film centres on Moncho and his coming-of-age experience in Galicia in 1936. Moncho develops a close relationship with his teacher Don Gregorio who introduces the boy to different things in the world. While the story centres on Moncho's ordinary coming-of-age experiences, tensions related to the looming Spanish Civil War periodically interrupt Moncho's personal growth and daily life.

The night of San Juan, Miguel murders his associate. Two elderly people are witness to the crime and predict that all of his dreams will come true thereafter. He will know the price he has to pay when he sees a black cat with a moon shaped mark on its forehead. Twenty-two years later a messenger begins to see all his dreams come true...

Doctor Beiral, torn apart by the internal struggle between his social persona and the dark instincts that torment him, manages to use his investigations to give life to the monster that he has long held within him.