When old friends from school start dying one by one, Sayree and Nataya begin to search for the secret of the letter that each of their friends received before death. Soon the two believe they are the next targets.
In 1977, there's a fight between soldiers and communists in a village along the border. Sak, a teacher in the village, loses his wife and his young daughter but his son is saved by Pew who later adopts him and changes his name to Tin.
