Jim Gillespie

A disgraced FBI agent with a drinking problem joins nine other troubled law enforcement officers at an isolated detox clinic in the wilds of Wyoming. But the therapeutic sanctuary becomes a nightmarish hellhole when a major snowstorm cuts off the clinic from the outside world and enables a killer on the inside to get busy.

As they celebrate their high school graduation, four friends are involved in a hit-and-run accident when their car hits and apparently kills a pedestrian on an isolated roadway. They dispose of the body and vow to keep the incident a secret, a year later somebody starts sending them letters bearing the warning "I Know What You Did Last Summer".