Possessed

A teacher had to return to work even when he is not ready to do so after a tragic incident that befall upon him. On the same day, a group of students went to a close by waterfall for a picnic. One of them stumbled upon a mysterious bottle and opened it. Back in their dormitory, all hell broke loose when one by one, the students got possessed. In order to survive, they have to work together and sacrifices have to be made.