Eun Su gets falsely accused of murdering her husband, a son of a conglomerate, and spends certain time in prison. While in prison though, she gives birth to her daughter, but she sends her daughter to the mother of her late husband, hoping her daughter will live a good life. However, things don’t turn out the way she wants.

Eun Su finds Mr. Yoon Sang Kyu, the former secretary of Chairwoman Kim, and demands to know where he hid her daughter. He tells Eun Su that her daughter is dead, but later confesses that he lied. He gives her the address of the family that adopted her daughter. When Eun Su sees a little girl coming out of the house, she runs to hug her. Right then, the girl’s father appears.

Eun Su can’t help but follow Woo Joo around. She tells Sang Kyu that she wants to live with her own daughter, but later realizes that she can’t support her as she’s an ex-convict. Se Mi returns to Korea and contacts Ji Kyung to see how Ji Min and Woo Joo are doing. She goes to see Woo Joo secretly, but Woo Joo runs away from her.

Ji Min learns that it was Se Mi that Woo Joo ran away from, and that Eun Su actually saved Woo Joo’s life. He apologizes to Eun Su and treats her to a meal with Woo Joo. When Eun Su hears that Woo Joo doesn’t have a mother, she forgets about leaving and decides to stay to become Woo Joo’s mom.

Eun Su plans her moves and appears in front of Ji Min as though it’s coincidental. She tries everything she can to win Ji Min’s heart, which makes him keep thinking about her. Meanwhile, Se Mi finds out that the woman Yeon Jun is looking for is the former daughter-in-law of Chairwoman Kim.

Eun Su becomes Woo Joo’s private art teacher, and they become close to each other. While spending time with Woo Joo, Eun Su runs into Mi Jin who used to be her cellmate. She asks Mi Jin to never tell Ji Min and Woo Joo that she’s an ex-convict. Meanwhile, Chairwoman Kim finds out whom Eun Su is seeing.

Woo Joo takes Eun Su to the art contest held by D.O Cosmetics. At the venue, Eun Su meets Chairwoman Kim, and Chairwoman Kim finds it strange that Eun Su is there with a kid. She tells her assistant to look into the kid and finds out who she really is. Meanwhile, Yeon Jun finally meets Eun Su, but he sees her when she’s with Ji Min.

Chairwoman Kim runs a DNA test with Eun Su and Woo Joo’s hair. Se Mi meets Eun Su and tells her to stay away from Ji Min. Eun Su has a good time with Ji Min and confesses her feelings to him. Meanwhile, Woo Joo wins first place in the art contest.

Ji Min asks Eun Su if she’s really Woo Joo’s birth mother. Eun Su confesses that it’s true she approached him and Woo Joo with an ulterior motive. Disappointed, Ji Min tells her he doesn’t want to see her ever again. Meanwhile, Mr. Yoon calls Ji Min to talk about Chairwoman Kim.

Mr. Yoon dies from the fall, and Eun Su thinks it’s Chairwoman Kim’s doing. Ji Min hears the full story of what happened to Eun Su 10 years ago, and he begins reinvestigating on the case of Jeon Gi Bum’s death. Meanwhile, Yeon Jun hands an important piece of information to Ji Min.

Ji Min decides to pretend he’s still dating Eun Su so that Chairwoman Kim wouldn’t approach Woo Joo. He warns her to stay away from Woo Joo, but she decides to make a confession on a news show that her granddaughter is still alive. Meanwhile, Se Mi meets up with Ji Min’s mother and tells her a shocking story.

Ji Kyung helps Se Mi meet Woo Joo secretly, but Woo Joo doesn’t feel comfortable when she’s with her mom. Se Mi gets an urgent call from D.O cosmetics, so Woo Joo is left alone at a restaurant. Chairwoman Kim then takes Woo Joo outside the city, making Eun Su think that Woo Joo is kidnapped.

After learning that Eun Su murdered someone, Woo Joo faints. She gets checked up at the hospital, and it turns out that she has a serious illness. She can only survive if she gets a lung transplant, but Ji Min is not a match. Eun Su gets tested to see if hers matches Woo Joo’s.

Chairwoman Kim stops the ethics committee meeting from being held and suggests to Ji Min another option to save Woo Joo. Ji Min is torn, as Chairwoman Kim made him choose between Eun Su and Woo Joo. Meanwhile, Yeon Jun finds the crucial evidence to bring down Chairwoman Kim.

Ji Min and Eun Su have finally come closer to the truth behind what happened 10 years ago. Chairwoman Kim is taken to the prosecution for questioning, but it seems she’s still trying to hide something. Meanwhile, Eun Su and Woo Joo get ready for the surgery.