This movie covers the final hour leading up to the Columbine High Massacre. On April 20, 1999, two boys from Columbine High School in Colorado embarked on a massacre and killed 12 students, one teacher, and injured 21 other students, before turning the guns on themselves.

When zero hour strikes, three kids are caught up in the mayhem of a violent outbreak as they escape from school and try to reunite with their parents.