When a huge meteor called Leonic falls to earth in Surin province, San and his old high-school friends are setting up camp nearby and manage to snap a strange shot of the event. The picture contains a clue that leads the group to mysterious deaths of two villagers, one of whom used to work for a secretive scientist, who's conducting experimental work with human organs -- possibly in cahoots with a Cambodian witch. Detective Bhichit and Narisara, a genetics expert, join the group to investigate the strange sequence of events.

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.