A group of mischievous high school seniors during detention at the library find themselves trapped in with a vengeful librarian and must survive the whole night or die trying.

By the way I would start the logline off with the character's being trapped

"When they are trapped in the school library by vengeful librarian, An Honor student, a Geek, a Jock, and an Outcast must put aside their differences and stop the madman before he kills them all"?