Dong-jin runs into Mi-jung, the girl who was branded as a witch in their high school. He follows her to her home without realizing it and sees how she's still suffering from the curse she's rumoured to have. Dong-jin decides to find out the law of the curse so he can help lift it and save Mi-jung.
Mi-jung, who couldn't stand the rumour of her being a witch and the boys from the same school getting hurt and dying, drops out of school. But the same rumour spreads in her village, leaving her no choice but to hide from everyone. Her father decides to take her to Seoul, but an unfortunate accident kills her father as well.
Dong-jin joins the statistics class and befriends Joong-hyuk at university, and they become best friends. He writes a statistics report to prove Park Mi-jung is not a witch, gaining the professor's attention. Dong-jin returns home during school break but learns the villagers have ousted Mi-jung from the village, breaking his heart. After graduating, he gets a job with Shine Solutions and becomes successful.
The statistics report Dong-jin wrote returns to him after his mother's death, and a battle within himself begins. He takes time off work and finds a place to live next to Mi-jung to get closer. Meanwhile, a victim of Dong-jin's work comes to get his vengeance, which makes him realize numbers aren't the answers to everything. Afterward, he returns to his hometown to find clues that will break Mi-jung's witch's curse.
Dong-jin returns to Taebaek in search of a clue that could break the witch’s curse on Mi-jung. With the support of his friends, he meticulously compiles information about the string of accidents and uncovers a disturbing pattern. As he digs deeper, he realises that he meets every condition of his hypothesis, leaving him filled with suspicion and uncertainty.
To uncover the missing years in his investigation, Dong-jin reaches out to Eun-sil, the one person who has been close to Mi-jung since their university days. With her help, he uncovers more accidents and deaths tied to her, strengthening his theory. As the puzzle pieces fall into place, Dong-jin realises the only way truly to validate his findings is to put himself to the ultimate test.
Dong-jin takes on a delivery job at the supermarket where Mi-jung regularly shops. Every Tuesday, as he delivers her orders, he begins to test the theory he's been developing about her. Gradually, he pushes the boundaries of his own rules, discovering just how dangerous it can be to remain within a ten-meter radius of her. Yet, despite the growing risks, his deepening desire to be closer to her and to linger in her presence threatens to draw him into ever greater peril.
Aware of the dire consequences of getting too close for too long, Dong-jin plunges into the river in a desperate attempt to save himself. However, Mi-jung recognises him, intensifying the danger he's already in. As he recovers in the hospital, Dong-jin turns to Producer Heo, seeking her help to identify a key variable in his hypothesis that might hold the solution he is desperately searching for.
