The heroine Hae-joo (Han Ji-hye) begins life in utter poverty. But despite being burdened with the secret past of her parents, she navigates treacherous waters and overcomes obstacles to achieve her dreams. Her childhood sweetheart Park Chang-hee (Jae Hee), son of the butler to a company chairman, also rises above his humble beginnings to become a successful prosecutor. Bright and playful Kang San (Kim Jaewon), the rival boss’s privileged grandson, returns to Korea after years abroad to find that he still carries a torch for Hae-joo.
The story starts with the murder of a scientist whose name and identity are unknown. On the other hand, his family is scared and worried. Wealthy Jang Do Hyun is revealed to be the murderer. He being the superior of the murdered scientist wears a mask of grief and takes part in the memorial service, only to take his junior’s wife as his own wife. Her girl child is robbed from her and given away to an unemployed and debt struck military junior of the head butler of Jang Do-hyun. Even though Jang orders for her to be killed his butler Park Gi-chul, because of his conscience is unable to do so. The story moves forward and we see a young Hae-joo,the murdered scientist’s daughter, living with a family that has an ill-mannered and complaining mother, as she believes her to be the husband’s illegitimate daughter. Park Chang Hee, the butler’s son, who is ill-treated by the owner’s son, has his own share of grief. Also there is Kang San, a charming, carefree and cheerful heir of the rival group of Jang Do-hyun, Haepoong. He is the only heir to his grandfather’s business as his parents are dead. They all meet under one roof at the local school where Kang San and Chang attend the same class. Due to their similar situations Chang Hee and Hae Joo start liking each other. However Kang San starts falling for Hae Joo because of her welding abilities and cheerful personality. Due to some regrettable situations and events, Jang finds out that Hae Joo is his wife’s daughter who he thought had been killed. So, he orders the butler to kill her. Chang Hee’s father kills Hae Joo’s father instead when the man puts himself between his adopted daughter and the butler’s vehicle.
On the other hand, Jang takes over Haepoong group by deceit and Kang San’s grandfather is jailed unfairly. Kang San moves to America for further studies. Hae Joo’s family also moves away from the village. As the story takes a leap in time, we see Hae Joo and Park Chang Hee as adults dating, with Jang showering respect and praises toward Chang Hee as he is now the public prosecutor, a strict one, in hopes that he will protect his company. Chang Hee’s father the often abused butler dreams that one day his son will become the son-in-law of Jang group by marrying Jang’s daughter. He is seen to be playing matchmaker too.
Jang’s company bags a contract with an American company which sends their head executive Ryan Kang to oversee the project. He turns out to be Kang San who has a big idea for Jang. He and Hae Joo meet at a night club and when she attends an interview for the Jang group. She and San work together after he reveals himself. They work together to build a new king of drill so that San can take his company back. But all their efforts are thwarted by the rivals. In the meanwhile San loses his job, gets stabbed, and loses his grandfather while Hae-joo struggles with her family and her growing feelings towards San.
Chang Hee under great humiliations and blackmailing from his father marries Jang’s daughter who is in turn in love with San. Chang Hee starts to play with Jang’s daughter for getting back at her dad. He also learns that his father was behind Hae Joos father’s death. After losing his only support, his grandfather, San starts living on the streets and working at a construction site. From great provocation and support from Hae Joo,he moves into her house and starts anew. He also starts uncovering Hae Joo’s father’s death facts and finds out her mother. After several attempts at uncovering Jang’s deceit by taking his wife’s and Hae Joo’s uncle’s help they succeed in getting evidence against Jang. Between this Chang Hee takes the seat of Jang group and starts sinking low. It is revealed that Jang is the murderer and also that he is Hae Joo’s biological father. Because of this revelation Hae Joo rejects San’s proposal, which he does after getting the patent rights registered for their invention. Later, however they both kiss and make up. At the end we see Chang Hee living with his father at a village while his wife visits him to say that she loves him. Hae Joo and Kang San leave in their ship to drill oil in the Pacific whilst he dons her finger with a huge diamond. Jang, the cause of so much heartbreak, kills himself.