The play is adapted from a novel written by Joan Leslie and is set in a girls' boarding school in Australia in 1900. At that time, British Christian culture was gradually infiltrating Australian life, arousing girls' desire to get rid of shackles. The idea of pursuing freedom is slowly spreading. One day, the conservative headmaster organized a dinner out and chose an uninhabited and dangerous cliff. It was this mysterious and strange place that engulfed three of the girls. They were never found again, and they just disappeared without a sound.