Although the fascists declared victory and took control of almost all of Spain in 1939, a retreating group of Republicans still fights a guerrilla war, hiding in the mountains. They are pursued by a detachment of the fascist army commanded by the cruel and sanguinary Captain Vidal. The fascist detachment is stationed in an old castle, next to a pan's labyrinth.
To that castle arrives the twelve years old Ofelia, accompanying to her pregnant mother ("sick of child", in Ofelia's words) who is the wife, by her second marriage, of Vidal. Ofelia's father is dead and she dislikes the idea of her mother being married to Vidal. She refuses to call him father or please him with her actions.