The Ghost is the story of Ji-won (Kim Ha-neul), a bright young student with a promising future ahead of her. Her past, however, is a different story. Something happened to her a while ago, and whatever it was, it left Ji-won with a blank memory. She has no recollection of who she is, her friends or her life before the incident… Through half-seen flashes of mysterious events, Ji-won begins to remember things. She also begins to see strange things around her: A little girl hides in her closet, only to disappear the next moment, dark figures loom in the shadows. She suspects that these scattered images and events are somehow connected to the past she cannot remember. When a young woman is found dead, Ji-won discovers that she was once friends with three other girls: Eun-seo, Yu-jung and Mi-kyung. Together these four girls formed an impenetrable alliance, and then... What did she do? Why does everybody look at her so strangely? And why can't she remember anything? Ji-won digs deeper into her past, hoping to find the answer. But as the old saying goes: Be careful what you wish for, you just might get it...