Even though the theme of lovers separated by war is always present during the main series, in this special episode, this theme gains a new approach, focusing in the anonymous people that have their letters returned because their beloved ones can't be found. The undeniable death knocks on the door of reality that many don't want to open, hoping to find their beloved one on their door, at dawn. It may be a common subject in romances throughout history, but many times it's hardly accessible. This episode brings the classical to the modern world. One person can not deprive himself from watching this episode. Same is applied to the main serie.
