Three years after the start of the Pacific War, Mahito's mother died in a fire in Tokyo, and another year later his father married her sister and sent his son to a family estate in the countryside. The head of the family works at a defense plant and is rarely at home, so the boy has to spend his days with his pregnant stepmother and in the company of elderly servants, and, from the very first day, he is haunted by a suspicious gray heron. One day the bird tells Mahito that it can take him to his mother, and lures him to a mysterious tower, around which many local legends swirl.