The disappearance of a high school girl in 1993 still remains unsolved as Sang-hyuk, who was in charge of the case, has disappeared from the human world for decades. Sang-hyuk is convinced that the culprit of the missing high school girl case and the culprit of the Inwang Mountain missing woman case are the same person, and he actively participates in the investigation. Meanwhile, Baek-ryeon...

Baek-ryeon goes to find the street she saw in her dream. Although it is her first time to see that street, she feels strangely familiar and her heart starts to ache. The more Sang-hyuk learns about his feelings for Baek-ryeon, the more he becomes afraid of approaching her. He doesn't believe he deserves her.

Sang-hyuk remembers Baek-ryeon saying she was an angel when she was drunk, and he secretly hopes that she actually is an angel. Meanwhile, Go Eun-seo, a missing woman from Mt. Inwang, calls Baek-ryeon and tells her that she is alive and asks her to come. Baekryeon goes alone to the address where Eun-seo is.