Yoon Oh is a student who is about to take college entrance exams for the 5th time but hopes to open a cafe as he works part-time at a coffee shop. Peach is his friend from Bangkok whom he had met in Phuket the previous year on a vacation trip. Peach informs Yoon Oh through text that he will be in Korea in a few days. However, when Peach arrives in Korea he feels lost and ends up in an isolated resort where he meets Yoon Oh's mother and then Yoon Oh himself later that day and learns about the bitter relationship between Yoon Oh and his mother.

It's been three days since Peach arrived in Korea but Yoon Oh still hasn't brought him to see the Winter Sea as promised. As Peach begins to whine, Yoon Oh decides to take him the next day. The next morning as Yoon Oh tries to step out of the Resort, an apparent clear barrier blocks his path, and his memory is struck with flashbacks of him being bullied by a bunch of students. Yoon Oh faints and the trip is put back. Later, a lady rings the doorbell and hands a box of Yoon Oh's belongings to Peach. Peach accidentally opens the box only to realize that Yoon Oh died before his arrival. His mind is left in chaos and he runs out with his belongings in utter fear.

Peach is unable to run away and he misses the Airport Bus, just then he acquaints Mario. Mario is also a ghost who has been around for 23 years. He explains to Peach how a deep resentment prevents spirits from moving to the afterlife and other possible occurrences that may occur to spirits like himself. Peach gets overdrunk as his mind is in disbelief and wakes up in Yoon Oh's mother's car who takes him to Yoon Oh's memorial and apologizes for not informing him sooner of Yoon Oh's death.

Yoon Oh successfully crosses the invisible barrier and is now able to walk out of the resort. Peach is helping Yoon Oh figure what resentment could possibly be holding back him on the mortal land, meanwhile Mario informs them that he must figure out the reason within 49 days of death i.e., 30 days from the present day else Yoon Oh will be trapped in forever. Yoon Oh expresses his wish to sing in college fest followed by Peach organizing a stage in the evening. Yoon Oh sings a self composed song "Ordinary Confession." At the end of the song Peach is so moved that he kisses Yoon Oh.

Investigation of Yoon Oh's death proceeds with the suspicion of suicide. Mario warns Peach of the forthcoming sorrow when Yoon Oh will disappear and he will be left with memories, regardless Peach wishes to open a cafe for Yoon Oh in the resort but Yoon Oh's mother wishes to sell the resort.

Yoon Oh questions Peach's intentions behind opening the café.

When Mario meets the daughter of Su Jin, something inside of him shifts.

Peach asks Yoon Oh on a date, but after visiting his memorial, Yoon Oh asks Peach an impossible question.

Sung Sook finds the strength to begin to right the wrongs of the past and takes accountability for her own missteps.