Autumn in My Heart

A family secret is revealed after a young girl gets hit by a car.

The parents on both sides of the family are upset when they find out that their daughter has been mistaken for the wrong one. Eun-soo's mother, Kyung-ha, wants to continue living with Eun-soo. However, one day, Shin-hye's mother Soo-nim blurts out the truth, and Shin-hye comes to Eun-soo's house. Eun-soo is shocked to find out that she is not her real daughter...

Each girl adjusts in her own way to living with her new family, and the echo of this trauma is still heard nine years later as the characters have grown to adulthood.

Joon Suh continues his search for Eun Suh, who develops a relationship with Tae Suhk.

Eun-soo shakes off Tae-seok's attempts to forcibly kiss her and runs off, only to be misunderstood by Manager Kim, who practically fires her. One day, Eun-soo and Joon-soo are finally reunited on the beach of memories, and they come to live together in Joon-soo's atelier.

As Joon Suh and Eun Suh draw closer, Yoon Shin Ae returns from America and has an awkward reunion with Eun Suh.

Joon-seo and Eun-seo gradually develop feelings for each other that are more than brother and sister. Joon-seo tells Yumi that he is leaving her, but Yumi declares that she will never give up on him. Eun-soo is asked by Yumi to befriend Joon-seo, and she decides to hide her feelings for Joon-seo and go out with Tae-seok.

Eun-seo and Joon-seo decide to become brother and sister again. Joon-soo decides to live with Yumi, and Eun-seo decides to go out with Tae-suk, and the two lie to each other and go hiking as a last memory, but heavy rain traps them in the lodge overnight.

Eun-seo and Joon-seo continue to hide their feelings for each other from everyone around them, but Tae-seok notices Eun-seo's feelings and visits Soon-im to formally ask her to marry him. At Soon-mim's request, the Yoon's decide to adopt Eun-seo as their daughter, but when Shin-hye tells her parents about Eun-seo and Joon-seo's relationship, the two elope.

After eloping, Joon-soo and Eun-soo spend happy times at the ranch. Joon-soo picks flowers for Eun-soo's birthday as a gift and proposes to her. The next day, they return home with Tae-seok, who has come looking for them, but when they are questioned by everyone, Joon-soo declares that she will marry Eun-seo.

When Tae-seok hears about Joon-seo and Eun-seo's marriage, he hates them both. His family all oppose their marriage, but Joon-soo and Eun-soo promise to live at the ranch. But then Yumi commits suicide and injures her arm, making her unable to paint for the rest of her life. Feeling responsible, Joon-soo vows to stay with Yumi forever.

Joon-soo and Eun-soo choose to part ways. Joon-soo then decides to hold a private exhibition at Tae-seok's hotel. Eun-seo lies to Joon-seo that she and Tae-seok are back together, but Tae-seok gets angry and takes Eun-seo to the exhibition and pretends to be her boyfriend in front of Joon-seo.

Shocked to learn that she has leukemia, Eun-soo visits Joon-soo, where she learns that Joon-soo is leaving for America with Yumi in two months. The only cure for the disease is surgery, which requires a huge amount of money, but Eun-seo is fired at Tae-suk's sole discretion.

When Eun-seo begs him to stay with her for six months, Joon-soo refuses, saying that he can't leave Yumi alone. Eun-soo is persuaded by Tae-seok to undergo treatment, and pretends that she and Tae-seok are going to elope, and leaves Joon-soo. Joon-soo is so sad that he drowns himself in alcohol, but one day he happens to find out that Yumi's right hand is completely healed.

Joon-soo heads to the ranch where he has fond memories of spending time with Eun-soo in order to sort out his feelings. At the same time, Eun-seo also visits the ranch, and the two spend happy time together. Tae-seok meets Sun-im and tells her about Eun-seo's illness, but Shin-hye, who happens to be visiting Sun-im, hears about it.

Just as the surgery schedule is set, Eun-seo falls into a coma. Yumi finally confides in Joon-soo about Eun-soo's illness, but Joon-soo is too sad to visit Eun-soo and instead burns her precious painting and says that she will go to America as planned. One day, Eun-seo's condition suddenly changes and she is diagnosed that tonight is the end of her life.