Look Up in the Sky (2012)

In the Fall of 2004, a high school Science class hiking trip to Mt. Rainier brings excitement and spontaneity of Senior Year. However, a professor's secret and an almost missed discovery changes each of the twelve on the trip. One of them disappears. It's 2014 when they are forced to reunite one by one to find out what happened and try to stop whoever's trying to kill them before it's too late.