Yoon Jae In is the daughter of Yoon Il Goo, the president of the Great Trading Company. Kim Young Kwang is the son of Kim In Bae, who is employed by Yoon Il Goo as the chauffeur. During Jae In's birthday party, Young Kwang hit a home run with the encouragement of Jae In. Il Goo finds out that Seo Jae Myung, the vice president of the company, is raising secret money. Il Goo forces him to turn himself in. During their struggle, the car runs out of control and goes into a river, causing Il Goo's death. Yoo Eun Joo, Il Goo's wife, rushes to the hospital with Jae In, but is badly injured in a car accident and goes into a coma on the way to the hospital. Jae In loses her memory and is sent to the monastery by In Bae.

Jae In grows up and becomes a nursing assistant. In the hospital, she runs into Young Kwang, who became a professional baseball player. Seo In Woo is Young Kwang's rival on the baseball field. They quarrel with each other in the hospital but are stopped by Jae In. Young Kwang does not know that Jae In saved him with blood transfusion and his harsh words upsets her. Jae In even missed the nurse exam to save Young Kwang. The nun gives Jae In the letters from In Bae and she mistakes him for her father.

Jae Myung becomes the president of the Great Trading Company. He is dissatisfied with the performance of his son In Woo, and urges him to give up playing baseball. Jae In is suspended for a week by the head nurse because of her involvement in Young Kwang and In Woo's quarrel. Jae In goes to Seoul to look for In Bae with the address on the letter. When she sees In Bae, he is harassed to repay his debts. Jae In calls In Bae her father and causes In Bae's family to misunderstand their relationship. Young Kwang has to leave the baseball team because of his injury. He comes across Jae In when he returns home and is disappointed in In Bae.

In Bae wants to tell Miss Oh about Jae In, but is chased by Jae Myung's men and killed in a car accident. The usurers break into Young Kwang's home to collect the debt and take the valuable items. Young Kwang has to give up playing baseball to pay the debt. Jae Myung wants Heo Young Do, the sales king within the company, to teach In Woo how to do business. However, Young Do only accepts those who enter the company through an open recruitment.

Young Kwang is not at ease as Jae In used her own savings to pay the debt. He tells her that he will find a job to make money. However, Young Kwang's mother Park Gun Ja already accepted Jae In's money against her will. Young Kwang and Jae In try many ways to look for a job but to no avail because of their poor reputation. In Woo does not want to work in the company and is badly beaten after saying no to his father. Jae In gets lost and Young Kwang goes to pick her up.

While trying to escape, Jae In meets Seo In Chul who is badly injured. She does not know In Chul is the one who kidnapped her and mistakes him as a victim. She sends him to the hospital for treatment. In Chul is greatly moved by her. Forced by his father, In Woo announces that he will quit baseball. In Chul offers Jae In a well-paid job as In Woo's private nurse. Young Do provokes In Woo and Young Kwang into joining the public recruitment of the company. In Woo gets drunk and comes across Jae Myung while back at his apartment.

Jae In goes to In Woo's apartment and finds him suffering from a panic disorder while answering Jae Myung's phone call, Jae In decides to be In Woo's private nurse. In Woo, however, asks her to work with him in the Great Trading Company. Young Kwang's elder sister, Kim Kyung Joo, hears from her lover, In Chul, that their father's death was caused by Jae Myung. Jae In's mother, Eun Joo, finally awakens after 17 years of coma. Eun Joo learns everything from Miss Oh and cannot accept what happened. Young Kwang, In Woo and Jae In attend the public recruitment of the Great Trading Company.

In Woo makes trouble for Young Kwang in order to knock him out of the examination. However, Young Kwang hangs on and gets the task done in the last second. Young Kwang knows why Jae In attended the recruitment and advises her not to get too close to In Woo. In Woo is shocked to find that Jae In is Il Goo's daughter and decides to hide her identity from his father. Gun Ja finds the letters and the bankbook, that reveals the money was remitted to Jae In by In Bae. She is so upset that she drives Jae In out of the house. Learning that Young Kwang is In Bae's son, Jae Myung is pleased with what In Woo did during the examination.

Jae In advises Jae Myung to treat In Woo better but is scolded by Jae Myung. In Chul leaves In Woo to decide Jae In's fate. In Woo fires Jae In in order to keep her away from danger. Under Young Kwang and Grandma's help, Jae In is forgiven by Gun Ja and moves back home. Miss Oh arranges physical treatment for Eun Joo, but is blamed by Jae Myung. Young Kwang meets the loan shark in the company. He is desperate for the job and begs Young Kwang to forgive him.

In Woo asks Young Kwang to stop Jae In from attending the interview, but Young Kwang refuses. Jae In carelessly loses her hiking shoes, which are necessary for the task. Young Kwang suggests that she buys a new pair in the market. On the street, Jae In happens to find Gun Ja doing a part-time job in the KTV. Gun Ja gets into trouble in the KTV and Jae In helps her to escape. Jae In promises to keep this a secret. Gun Ja changes her opinion about Jae In and begins to accept and welcomes her.

In Woo's mother is dissatisfied with Jae In and threatens to fire her. Miss Oh finds Gun Ja and asks her about things that happened 17 years ago. Gun Ja recalls In Bae's words. Jae Myung asks to be Young Kwang's customer in the examination. Young Kwang tries every means to sell the product to Jae Myung, and even dresses up and acts like a clown. However, he fails to persuade Jae Myung. Gun Ja goes to the hospital to visit Eun Joo and surprisingly finds out that Jae In is actually Eun Joo's daughter. Young Kwang confesses to Jae In while drunk.

Gun Ja feels guilty when she knows that In Bae got the money by betraying Jae In and used the money to open the noodle shop. During the company's product launch, In Woo's illness suddenly attacks him but no medicine is at hand. Jae In helps him to recover under the guidance of Dr Go. Young Kwang uses some tricks to make Jae Myung laugh in front of people. Jae In learns the knowledge of the products from other staff and impresses the interviewers. In Woo uses his power and influence to threaten one of the interviewers. As a result, they all pass the second interview. In Woo makes a sincere apology to Jae In and asks her to be his private nurse again.

Young Do delivers the information containing clues left by In Bae and hopes to unravel the riddle. Jae Myung threatens Young Kwang by exerting force and violence. Feeling depressed, Young Kwang holds Jae In's hand to seek emotional relief. However, this scene is caught by Gun Ja. Gun Ja's sudden change in attitude and care for Jae In surprises the whole family. In Woo knows Jae In is sick and comes to visit her, which makes Young Kwang jealous. While seeing Jae In's childhood photos in Jae In's room, Young Kwang starts to question Jae In's real identity.

Young Kwang sees Jae In's photo in Il Goo's columbarium and confirms Jae In's identity. Young Do visits Gun Ja's noodle restaurant to ask about Jae In, but Gun Ja gives no answer. Jae In offends an important client of the company, but manages to resolve the crisis with her knowledge. Jae Myung finds out Jae In's identity and becomes furious at In Woo covering up the truth. Young Kwang tells Young Do the answer to the riddle and decides to compensate for his father's sins by returning Jae In the position she was supposed to have.

Jae Myung tells Jae In that she is Il Goo's daughter and In Bae was the guy who abducted her. Jae In cannot accept that and seeks confirmation from Gun Ja. However, Gun Ja makes up a story by saying In Bae abandoned her. Young Do tells Young Kwang that In Bae's accident was caused by In Chul's chase. Jae Myung brings Jae In back to his family and takes good care of her. Jae In begs him to stop creating obstacles for Young Kwang's family, and Jae Myung has no choice but to make a concession. In Woo's mother hates Jae In and throws away all her clothes.

Young Kwang wants to take Jae In away and flee to a faraway place, but is stopped by In Chul. Young Kwang gets beaten up by In Chul's men and Jae In has to agree to go back. In Woo opposes his father for making use of Jae In and is beaten. Joo Dae Sung dislikes Young Kwang and always creates trouble for him during the training. Learning that Eun Joo has recovered, Jae Myung attempts to transfer her to another hospital by force. Gun Ja tells Jae In that her mother is still alive and that Jae Myung has been cheating her. Jae Myung requests that Jae In sign the written content for the financing plan, but is stopped by In Woo.

In Woo succeeds in disobeying his father, and this surprises everyone. Jae Myung buys the noodle shop to drive Young Kwang and his family away. Young Kwang promises to fix the tent for Dae Sung's customer, Old Man Hwang. While Young Kwang and his colleague are looking for the part which has gone out of production, someone makes trouble for them in secret. Young Kwang finds the part by chance and helps Old Man Hwang fulfill his wish. Jae In signs the document in exchange for the title deed of the noodle shop and returns the title deed back to Gun Ja. Jae In goes to the hospital to look for her mother but misses her. It turns out that Old Man Hwang is the investor Jae Myung is looking for.

Jae Myung holds an emergency meeting with the members of the board of directors and proposes a plan for capital increase, which gets a consensus amongst all attendees. At this moment, Eun Joo arrives and objects to the proposal. Filled with anger, Eun Joo stabs Jae Myung with a knife and falls into a coma again because of exhaustion. Jae In finally meets her mother and gets the truth about the accident which happened 17 years ago from Miss Oh. Young Do tells Young Kwang that he can only defeat Jae Myung when he gets money and buys the shares. Young Kwang pours out his troubles to Old Man Hwang and he decides to help Young Kwang.

Miss Oh hires three lawyers to help Jae In deal with her property affairs. Jae In goes to Jae Myung's house and declares war with him. Young Kwang is blamed for not delivering clothes as per the customers' order. With his colleagues' help, he is able to send out the goods in time. Jae In reveals her identity at the businessmen's party and accuses Jae Myung of abandoning her 17 years ago. To bare his heart, In Woo kisses Jae In at the party, which is seen by Young Kwang. Young Do suggests that Jae In makes a plan for the company's future before the revenge. Old man Hwang asks Young Kwang to use his life as a guarantee for the loan.

Young Kwang agrees to Mr. Hwang's condition. Mr. Hwang lends money to Jae In, making Jae Myung very angry. Jae In blames Young Kwang for sacrificing his life as guarantee. Young Do and other colleagues set a trap and catch the traitor. In Woo is beaten by someone and is badly injured. Young Kwang becomes the suspect. Young Do protects Young Kwang at the expense of closing down his department. Inspired by a senior employee, Jae In decides to give up the loan and announces that she will give all her shares to the company's staff.

In Chul advises Jae In to give up transferring her shares but is rejected. He breaks Young Do's team on the grounds of staff transfer. Jae Myung threatens Jae In that she will lose everything. However, In Woo threatens Jae Myung with his son if he hurts Jae In. Young Kwang's grandma is diagnosed with Alzheimer's disease. Jae Myung gives an order that any staff who accept Jae In's shares will get severe punishment.

In order to capture the real criminal, In Woo calls the police. Jae Myung watches the video of the criminal and no longer trusts In Chul. Young Kwang's grandma goes missing and the whole family looks for her. Finally, Jae In finds her and grandma says that she was waiting for Jae In to come back. Jae In is greatly touched. Jae In fails the war of shares and cannot find a way out. In Chul puts forward an alliance and fight against Jae Myung together.

Jae In asks Jae Myung to take the blame and resigns. Jae Myung admits about raising secret funds and evading tax. His words are broadcasted to the company and he loses all the staff's trust and support. Finally, he is arrested by the prosecutor Miss Oh. Young Kwang is chased by the real criminal. At the critical moment, policemen arrives and save him. The criminal confesses that he was instigated by Jae Myung. In Woo is surprised and upset about his father's doing.

In Chul finally becomes the vice president of the company. In Woo takes over the baseball team and begins to work in the company. Eun Joo wakes up and finally recovers. Jae In passes the nurse examination and becomes a real nurse. She finally wins the head nurse's recognition through her efforts.