A group of mischievous high school students scheme to put the fright into their least favorite English teacher. But their prank takes a horrible wrong turn, and the teacher ends up dead. The kids didnt do it, but all the evidence points their way. Now, the race is on for them to expose the actual murderer before theyre looking at final exams -- from behind bars. based on the novel by Lois Duncan ("I Know What You Did Last Summer").