The story is about Han Jung-suh (Choi Ji-Woo) and her best friend, Cha Song Joo (Kwon Sang-woo). As childhood friends, Han Jung-suh and Cha Song Joo had a special bond that blossomed into love. They were always together, even when Cha Song Joo's father died and when Han Jung-suh's mother died. After a few months, Han Jung-suh's father met an actress and fell in love with her. The two were married and Han Jung-suh was very happy that her father was finally smiling, stating to Cha Song Joo that she had not seen her father smile like that since before her mother died. After her stepmother moved in, she brought her real daughter, Han Yoori, and her son, Han Tae-Hwa, into her new family, but when Han Jung-suh's father left for work, her stepmother assaulted Han Jung-Suh. She thwarted Han Jung-suh's attempts to study abroad with Cha Song Joo, who left to America to study abroad alone, leaving a sad Han Jung-suh behind. Hang Jung-suh was left alone to suffer in the silent cruelty of her step sister, Han Yoori, and new step mother. Han Jung-suh's cruel stepmother plotted for her own daughter, Han Yoori, to win the affections of Cha Song Joo, who came from a rich family, and thwarted any attempts of Han Jung-suh to be with Cha Song Joo. All the while, Han Jung-suh tried to be nice to her new step brother, Han Tae-Hwa, who mistook this friendship for affection. Han Tae-Hwa fell in love with young Han Jung-suh.
Cha Song Joo was in America for three years. On the night of his return, an excited Han Jung-suh rushed to greet him. A jealous Han Yoori tried to stop the two lovebirds from reuniting so, as they raced to the airport, Han Yoori spotted Han Jung-suh and intentionally ran her over with her car. Han Jung-suh, then unconscious, was taken to the hospital where a group of people had just died in fire. Han Yoori swapped Han Jung-suh's ID with one of the people that just died in the fire to fake her death. She took the real Han Jung-suh to her biological father's home. Han Tae-Hwa, still in love with Han Jung-suh, found out what Han Yoori had done, but saw the accident as a chance to run away with Han Jung-suh, who would otherwise return to Cha Song Joo. Han Yoori and Han Tae-Hwa, along with their father, were the only ones who knew what had happened, and Han Tae-Hwa's father agreed to cover for his daughter. Han Jung-suh lost her memory, and Han Tae-Hwa moved them away and changed their names. Meanwhile, at the scene of the crime, Cha Song-Joo found a blood-stained picture of the two of them from their youth.
Five years after the accident, it seemed that Han Yoori had won the battle of love; she was soon to be engaged to Cha Song Joo. The day before getting together with the families to arrange the engagement, Cha Song Joo decided that he needed to let go of Han Jung-suh. He went to the carousel they used to ride as children and whispered a wish to see Han Jung-suh just once more. He looked up and saw her on the carousel. Han Jung-suh who was now Kim Ji-soo (after being renamed by Han Tae-Hwa, now Han Chul-soo). Cha Song Joo rushed to Kim Ji-soo and told her that she is Han Jung-suh, but she did not believe Cha Song Joo's words. However, Cha Song Joo believed that it really was Han Jung-suh, and determined to make her remember her past and the love she had for him. Through a series of events, he and Han Jung-suh became close. Han Jung-suh's family also met her and were shocked by her similarity to the daughter they thought was dead. Han Yoori and her mother, who both knew the truth, were terrified that Han Jung-suh would regain her memory, ruining their plans. However, Han Jung-suh did not remember her past life and Cha Song Joo finally realized that he was mistaken.
Fortunately, one day, Han Jung-suh regained her memory when Han Yoori nearly hit her with her car again, when Han Jung-suh ran in front of her vehicle. She rushed to tell Cha Song Joo. She went back to Han Tae-Hwa and he told her the truth—the accident, her memory loss, and everything else, and forgave him, as she knew he did it out of love, and tried to forget the memories. Luck seemed to be on the side of the two lovers, Han Jung-suh and Cha Song Joo, until Han Jung-suh discovered she has eye cancer. Depressed, she went to Han Tae-Hwa and told him to take her away from Cha Song Joo, since she could not bear to see him in pain, because she noticed she was losing her vision. Gradually, Han Jung-suh's vision deteriorated into blindness. Determined to not cause any more sadness to his stepsister, Han Tae-Hwa told Cha Song Joo and his family the truth, with Han Tae-Hwa's biological father providing further evidence. Han Yoori was arrested and her mother was sent to a mental institute. Han Jung-suh married Cha Song Joo, who was now blind.
Over the few weeks that followed, Han Jung-suh and Cha Song Joo spent quality time together as husband and wife; Han Tae-Hwa and Cha Song-Joo even became good friends. Han Jung-suh told Han Tae-Hwa that her one wish was to see Cha Song Joo's face for one last time. Both Cha Song Joo and Han Tae-Hwa (separately) asked a doctor to allow them to give Han Jung-suh one of their corneas, but the doctor informed them that they were not allowed to take corneas from live donors. Han Jung-suh left the hospital disappointed, while Han Tae-Hwa thought pensively about Han Jung-suh's last wish. He decided that he wanted to grant that wish at all costs and began to set in motion his plan. He created fake pictures of himself and a girl in France, wrote letters to be sent later, and told his friends and family that he would be going to Paris, France for his art and was not sure when he would return. What everyone did not realize was that Han Tae-Hwa decided to commit suicide in order to donate his cornea to Han Jung-suh because of everything he, his mother, and sister took away from her. He intentionally created a car accident to cause his death. After his death, Han Jung-suh had the operation and was able to see again. However, Han Jung-suh later on found out that the cancer had already metastasized. Though Cha Song Joo wanted her to pursue all the chemotherapy treatments to live, she decided that she would much rather spend time with him than "die in a hospital". She also found out about Han Tae-Hwa's sacrifice for her and decided to only see things that are good and beautiful. Han Jung-suh also visited Han Yoori in jail and her stepmother in the hospital, shortly before her death. Han Jung-suh died a few days later, at the seaside near her childhood house, in the arms of Cha Song-Joo.
The epilogue shows Cha Song Joo playing a tune that he used to play for Han Jung-suh during their childhood. At length, he stands up, asking Han Jung-suh if she can hear him.