In a gloomy era of Taiwan under Japanese rule, there's a noble family, the mother of the twins of different sexes died early, and their father works for the government away from home. YU, the twin brother, have nightmares every night about being drowned by someone. He is lonely and longing to talk to his sister, but he could not meet her. Because AMEKO, the twin sister, has been in illness isolation since childhood. Things become strange while their cousin WEN CHENG was returning from Japan. YU finds out a big secret of the whole family, about his sister and the killer in the dream.