Jin Sun-mi (Chae Rim) is a lovely college student who lives with her upper-middle-class widowed father. She has a happy childhood with her best friend Kim Woo-jin (Han Jae-suk). Life changes radically for Sun-mi when her father decides to support Heo Young-mi (Kim So-yeon), a beautiful girl the same age as Sun-mi.
Young-mi became an orphan when her father, an alcoholic who frequently abused her, dies in an accident while working for Mr. Jin's (Sun-mi's father) construction company. Young-mi has grown up in poverty, but she is not a humble person. She's arrogant, greedy and full of resentment. She initially becomes friends with Sun-mi, but eventually envies her for all she is and has, even Woo-jin's love.
Young-mi becomes Sun-mi's rival in every aspect of her life. First, Young-mi steals Woo-jin from Sun-mi, then tries to take over her job at a very important TV network as they both dream to be famous news anchorwomen. She finally turns her eyes on Sun-mi's new boyfriend, Hyung-chul (Jang Dong-gun), one of the network's top executives, whom Sun-mi met during a trip to London. However, Hyung-chul's love for Sun-mi is stronger than Young-mi's estimation. Meanwhile, Woo-jin suffers of a broken heart as Young-mi makes his life miserable and finally dumps him so she can chase Hyung-chul, even though it hurts her just as much since she does not love him and is only after him for her career's sake.
The climax of the plot comes when a former lover of Young-mi appears and threatens to reveal her deepest secret should she not return to him: a dark past as a prostitute. Since the gangster did not succeed in his attempts, he decides to kill Young-mi. Woo-jin dies while saving her life. However, all of Young-mi's treachery is exposed. Losing everything and heartbroken because of Woo-jin's death, she attempts to commit suicide, but her efforts are frustrated when she is found unconscious by a group of nuns on the shore of the Han River. When Young-mi wakes up, she suffers from amnesia and has lost almost all memories of her past.
The drama ends with a happy reconciliation between Young-mi and Sun-mi, who cries beside Young-mi, forgiving her for the misunderstandings between them since they met. Finally, Hyung-chul swears eternal love and proposes to Sun-mi right in the middle of a street, asking her not to move to London.
