Lim Ji Sub

While under heavily armed guard, the dangerous convicts aboard a cargo ship unite in a coordinated escape attempt that soon escalates into a bloody, all-out riot. But as the fugitives continue their brutal campaign of terror, they soon discover that not even the most vicious among them is safe from the horror they unknowingly unleashed from the darkness below deck.

In the prestigious Shinha High School, there is a secret hidden between the third and fourth periods. There are 3.5 classes where time goes 10 times slower and 10 minutes becomes 100 minutes! Baek Ah-jin accidentally enters the 3.5th period and meets Kang Da-won, a male student who was trapped there. To escape Dawon from the 3.5th period, Ahjin solves the mystery hidden there. But there are people in the school who try to hide 3.5 classes...