The 19-year-old girl Jie Yi (Maika Monroe) is beautiful and charming. She longs for a romantic and beautiful youth love, but she never thought that a great disaster would suddenly come. She went out on a date with the boy Hugh (Jake Weary), during which Hugh showed a panic. On that blurred night, Jie Yi was treated rudely by Hugh after the kiss, and then learned the reason for Hugh's panic. It turned out that there was always an invisible "person" following Hugh. TA can change the appearance of anyone and aim to kill Hugh. The only way to get rid of TA is to transfer it to others through sex. Since then, Jie Yi has been in panic all the time. Her sister Kelly and friends Paul, Yara and others are worried about her, but the invisible tracker appears anytime and anywhere. TA is the original sin that Jie Yi cannot get rid of, and it is a terrifying shadow projected in the depths of her soul...