12-year-old girl Ophelia (Ivana Baquero) has a brutal fascist officer stepfather, Vader (Sergi Lopez). Vader's mission is to suppress the rebels and research various torture instruments to torture and kill the captured dissidents. Ophelia witnesses unpleasant events every day. Seeing her cold stepfather and his gang doing evil every day and enjoying it, and her mother being pregnant and sick in bed, Ophelia, troubled by loneliness and the pain of witnessing atrocities, began to indulge in her own fantasy to comfort herself. One day, Ophelia met the guardian of the maze, Pan (Doug Jones). Pan told her that she was actually a lost princess of the fantasy kingdom, and to restore her identity, she must pass three dangerous tests.