Two years after the last Southport massacre, Julie James and Carla Wilson are still searching for the now-fugitive killer, Stevie Ward. After the last two survivors are murdered, the clues lead Julie to a nearby town where a new group of teenagers have made the grave mistake of keeping a dark secret. A year ago, they killed the most popular girl in school after attempting a cruel prank on her, framing her boyfriend and getting away with it. Now, they are receiving a familiar message: "I know what you did last summer."