The Setup (Eps 1–5): High school shaman Seong-ah sees transfer student Gyeon-woo walking upside down, marking him for death in 21 days. After Gyeon-woo's grandmother dies, suicide spirits attach to him. Seong-ah discovers that holding Gyeon-woo's hand acts as a physical talisman to keep evil forces away. The two fall deeply in love.
The Escalation (Eps 6–10): Greedy shaman Yeom Hwa awakens a powerful spirit from an abandoned house in Bongsu-dong to build her own power. The spirit, Bong-su, possesses Gyeon-woo's body. In Episode 10, when Yeom Hwa's ritual goes haywire, Seong-ah's mentor General Dongcheon sacrifices her life to absorb the dark curse, leaving Seong-ah heartbroken and powerless.
The Climax & Resolution (Eps 11–12): To free Gyeon-woo from Bong-su, Seong-ah selflessly draws Bong-su into her own body and vanishes. Gyeon-woo spends three years tracking her down. In the finale, Gyeon-woo confronts possessed Seong-ah; he enters her dream world and learns Bong-su was a young Korean War soldier named Jang Yoon-bo who died grieving for his mother. By speaking his real name with respect, Gyeon-woo and Seong-ah allow Bong-su to finally ascend in peace. Yeom Hwa sacrifices herself to seal the abandoned house.
Seong-ah reclaims her full shamanic divine powers ("Seonnyeo"). Years later, Gyeon-woo becomes an Olympic archer and Seong-ah continues as a fulfilled shaman; they live happily together in mutual love.