Stairway to Heaven

Jeong Seo moves in with her new siblings, Yu Ri and Tae Hwa, after her father, Professor Han, marries actress Tae Mi Ra. Yu Ri and her mother often mistreat Jeong Seo out of jealousy. Jeong Seo remains focused on her plan to study abroad with Song Ju, the person she loves and depends on.

Yu Ri and Mi Ra stop Jeong Seo from leaving for her overseas studies and confine her in the attic on the day Song Ju departs. Yu Ri also intercepts letters that Song Ju had sent to Jeong Seo. At the same time, Pil Su visits Tae Hwa on her birthday with a pair of sneakers, where he meets Mi Ra, while Jeong Seo makes a seaweed soup and prepares a gift for Tae Hwa.

Jeong Seo meets Song Ju upon her return to Korea, but tensions arise when Yu Ri, while under the influence, accidentally hits Jeong Seo with her father's car. To seek help from her biological father, Yu Ri stages a crime by placing Jeong Seo's ID in a dead body's clothing, resulting in Jeong Seo being declared officially dead.

Song Ju returns to Korea and becomes president of a Global Corporation affiliate. She and Yu Ri plan to announce their engagement during the company's foundation ceremony. While at Global Land, Song Ju encounters Jeong Seo and asks if she is Han Jeong Seo.

Yu Ri is devastated when Song Ju fails to appear at a ceremony where he was to announce their engagement, leading her to attempt drowning in a river after leaving him a note. Meanwhile, Jeong Seo has no memory of her past life as Kim Ji Su, and finds herself repeatedly encountering Song Ju.

Jeong Seo learns that Song Ju is the president of the company she has joined. Song Ju takes her to her old family home, where Jeong Seo meets her biological father. At the same time, Tae Hwa grows uneasy after seeing Jeong Seo exit Song Ju's car.

Song Ju persuades Jeong Seo to meet her original family to see if they recognize her, while Cheol Su tries to stop her from doing so. Jeong Seo presents a new fabric design for the upcoming season, but Song Ju encourages her to develop something more refined. At the same time, Yu Ri and Tae Hwa become worried that Jeong Seo may soon regain her lost memories.

Jeong Seo introduces a new product concept and receives favorable responses, while Song Ju arranges a surprise company dinner for the brand development team at a club. On her way to meet Tae Hwa, Yu Ri almost collides with Jeong Seo in her car, causing Jeong Seo to remember a previous accident.

Jeong Seo, having regained her memory, attempts to speak with Song Ju, but Yu Ri intervenes and takes him away. Meanwhile, Tae Hwa prepares to confess the truth to Jeong Seo, while Jeong Seo decides to confront Mi Ra and Yu Ri about her restored memories. Chairperson Min orders Jeong Seo to resign from her position immediately.

Jeong Seo returns home and finds Tae Hwa unconscious. After leaving to go to her inn, she is visited by Song Ju, and the two go out drinking. Although Jeong Seo reveals her true identity, Song Ju remains unaware. Determined to escape, Jeong Seo plans to take Tae Hwa far away.

Jeong Seo is reunited with her family and resumes her job, where she is encouraged by Song Ju to attend his engagement to the woman he loves. Tae Haw urges Jeong Seo to marry Song Ju, while Mi Ra secretly works to stop the engagement.

As Song Ju is about to propose to Jeong Seo, Tae Hwa's unexpected arrival prompts Jeong Seo to leave. The engagement proceeds in her absence, with Song Ju giving the ring to Yu Ri instead. Mi Ra supports Yu Ri, who becomes distressed upon discovering that Song Ju's actual feelings are for Jeong Seo.

Mi Ra suggests that Jeong Seo marry Cheol Su during a dinner with Song Ju. After the dinner, Song Ju, who has become drunk, encounters Jeong Seo and insists she stay at a cabin where Cheol Su is also present. While at the cabin, Jeong Seo falls ill, prompting Cheol Su to leave her and contact Song Ju.

Song Ju publicly expresses his love for Jeong Seo and promises to marry her, after which he resigns as company president and relocates to a dilapidated motel. At the same time, Mi Ra schemes to disrupt Tae Hwa's life in an effort to compel Song Ju to marry Yu Ri, leading Tae Hwa to confront Yu Ri upon uncovering her role in the matter.

Jeong Seo begins experiencing blurred vision and consults an optician, who advises her to see an ophthalmologist for further evaluation. At the same time, Global Corporation is dealing with a leadership crisis after Song Ju, the company's designated heir, resigns. Jeong Seo tries to persuade him to reverse his decision.

Tae Hwa goes to Jeong Seo's home and informs his family about the accident. A doctor explains that Jeong Seo has a 50% chance of survival if he undergoes eye extraction due to tumors. Choosing to spend his last day with Song Ju, Jeong Seo begins to come to terms with the possibility of his own death.

Jeong Seo lives in a beach house and is dealing with the grief of losing Song Ju. Tae Hwa tells Song Ju that Jeong Seo is about to lose her vision and decides to sell his imitation artworks to raise money for her surgery, which results in his arrest by the police in Seoul. Song Ju travels to the beach house.

Tae Hwa is arrested by the police, which leads Song Ju to go to the beach house, where Jeong Seo mistakenly identifies him as Tae Hwa. Song Ju then takes Jeong Seo to Seoul and reiterates his intention to marry her. Both Song Ju and Tae Hwa urge Jeong Seo to undergo surgery to remove tumors.

Song Ju announces his engagement to Jeong Seo at a gathering, but the event becomes tense when Mi Ra reacts with anger. Tae Hwa and his father arrive and reveal details of a past incident, including the circumstances of Jeong Seo's accident. Both Song Ju and Tae Hwa express their willingness to donate their corneas to Jeong Seo.

Tae Hwa deceives Jeong Seo by telling her he is going to France to study art, then commits suicide so she can receive his corneal transplant. Regaining her sight, Jeong Seo lives happily with Song Ju, and together they establish a foundation in Tae Hwa's honor. However, Jeong Seo soon begins to experience health issues again.