Movie Story : When four outcast teenagers are sentenced to summer detention, they are assigned to clean up their high school after a horrific incident. They soon find themselves locked inside, stalked through the ravaged hallways by a macabre gang disguised as the Four Horsemen of the Apocalypse. As they fight to survive, each must face supernatural echoes of past traumas they have tried hard to bury, and they may be doomed to relive them.