It's Una's first day of school ever. Because she doesn't understand that you're not meant to talk loudly, she gets Pax, Keitu and herself into detention. T-Man didn't get into trouble, but when a vicious acid-rain shower starts, all four of them are trapped in the school. And when the school's roof starts leaking the burning acid, the gang have to think fast and get over their arguments if they want to survive.