The Mystery Housemaid

Sang Chul hires Bok Nyu as a housekeeper when taking care of the house becomes difficult after his wife's death. Director Hong Bun Nam from the agency warns Sang Chul to be careful because Bok Nyu does anything she is asked. Meanwhile, Sang Chul's sister-in-law, Na Young, promises Hye Gyeol, her niece, to let her meet her mother when Hye Gyeol says she wants to meet her dead mother as her birthday gift.

Han Gyeol finds out that her mother, Sun Young, committed suicide because her father, Sang Chul, was having an affair. After Han Gyeol learns her father has been cheating, she visits his father's mistress, Song Hwa, and shows her mother's suicide note to her. Meanwhile, Sang Chul is uncomfortable with Bok Nyu, so he goes to the employment agency to request to replace Bok Nyu with another housekeeper.

Han Gyeol shows her mother's suicide note to her younger siblings and tells them that she cannot live with their father, Sang Chul, and leaves with them. After leaving her house, Han Gyeol and her siblings stay at their grandfather's house. Meanwhile, Hye Gyeol visits Bok Nyu and asks Bok Nyu to kidnap her to bring her family back together.

The four siblings ask their dad, Sang Chul, to leave the house. And they want Bok Nyu to stay with them and ask Sang Chul to allow her to work for them again. Meanwhile, Sang Chul explains to Bok Nyu that it was a misunderstanding when she caught him with Song Hwa. Geum Chi, Sang Chul's father-in-law, accidentally sees Sang Chul and Bok Nyu and becomes suspicious of their relationship.

Han Gyeol goes to meet her father, Sang Chul, to discuss about Bok Nyu. However, Han Gyeol is furious when she sees an engagement ring in Sang Chul's room. Meanwhile, Du Gyeol accidentally watches a pornographic video while searching for Park Bok Nyu on the Internet. And he is caught by Bok Nyu while watching it.

Du Gyeol and Se Gyeol ask Han Gyeol to let their father come back home, but she wants to get revenge on Sang Chul. Bok Nyu tells Han Gyeol that what parents are scared of the most is their child getting ruined. Meanwhile, rumors spread throughout the school that Han Gyeol is doing teenage prostitution and she runs away from home.

Soo Hyuk helps Han Gyeol to get away from the situation that she was misunderstood as doing teenage prostitution, and he asks Han Gyeol to let go of what he did to her. After that, Han Gyeol quits the band. Meanwhile, the four kids ask Bok Nyu about her family. And Bok Nyu answers that she killed her own family.

After Sang Chul loses Dad's stone, he orders Bok Nyu to postpone Hye Gyeol's play in her kindergarten. Meanwhile, Choi Kyu Dong is getting engaged to another woman and dumps Song Hwa. Then Song Hwa finds herself in a situation where she has to submit her resignation letter, so she goes to Sang Chul to ask for help.

Han Gyeol and her siblings feel suspicious of Bok Nyu and suspect that she might be the reincarnation of their mom. So, they try to do the ghost test. Meanwhile, after getting dumped by Sang Chul, Song Hwa comes to Han Gyeol's school to meet with her. Song Hwa tells Han Gyeol that she still wants to be with Sang Chul and asks Han Gyeol if she would accept Song Hwa becoming a mother for her and her siblings.

After Bok Nyu tells Sang Chul's family about her past, she quits working for his family as a housekeeper as promised. Sang Chul visits Bok Nyu and asks her if his family can be her reason to live. Meanwhile, Do Hyung offers Sang Chul a job at his company. Sang Chul accepts the offer and happens to work together with Song Hwa again.

Do Hyung invites Sang Chul and Song Hwa to his house for dinner. Sang Chul and Song Hwa are surprised to see an unexpected person at Do Hyung's house. Han Gyeol sees her father leaving Do Hyung's house with Song Hwa, and has suspicions again about their relationship. Meanwhile, Woo Jae accidentally sees Bok Nyu going to Do Hyung's house with an oil container and calls Han Gyeol to tell her about it.

Hye Gyeol tells Bok Nyu she wants to help her with anything in the kitchen. While helping Bok Nyu to make cookies, Hye Gyeol burns her hands in the oven. Bok Nyu is frightened and runs to the hospital carrying Hye Gyeol, even forgetting to wear her shoes. Meanwhile, Do Hyung tells Sang Chul that he wants to make Bok Nyu smile and asks Sang Chul for help.

Sang Chul's children ask Bok Nyu to be a mom to them. Song Hwa brings Sang Chul to her house because he passed out from being drunk. Song Hwa calls Bok Nyu and tells her to come to pick up Sang Chul because he is in her place and to make Bok Nyu see her with him. Meanwhile, Han Gyeol asks Bok Nyu to find out why Song Hwa cannot be a mother to her.

Han Gyeol and Woo Jae find out that Soo Hyuk works at a bar. So Han Gyeol asks her aunt, Na Young, to take Soo Hyuk out of the bar. Meanwhile, Bok Nyu asks Song Hwa to dig up on CEO Jang Do Hyung. Song Hwa asks Bok Nyu what kind of person Seo Ji Hoon is and Bok Nyu tells her about what Seo Ji Hoon did to her in the past.

Bok Nyu tells Song Hwa that she knows that Jang Do Hyung is Seo Ji Hoon. Bok Nyu also asks Song Hwa to do as Jang Do Hyung asks and to be careful with him. Meanwhile, Sang Chul tries to stop Do Hyung from having a relationship with Bok Nyu. Song Hwa then tries to turn Sang Chul's interest in Do Hyung to her by telling him she was involved in Sang Chul's wife, Sun Young's death.

Bok Nyu accepts Do Hyung's proposal and decides to marry him. Sang Chul and his children are worried about Bok Nyu getting married to Do Hyung. Meanwhile, Hye Gyeol doesn't want to lose Bok Nyu, so she goes to Do Hyung's house alone and tries to negotiate with him about Bok Nyu. Bok Nyu fears that Do Hyung will do something to Hye Gyeol when she sees Hye Gyeol start to become fond of Do Hyung.

Sang Chul learns that Bok Nyu is planning to quit being a housekeeper and is planning to reveal that Do Hyung is Seo Ji Hoon. Then Sang Chul visits Song Hwa, who is leaving Korea, to ask for her help. Meanwhile, Bok Nyu goes on a vacation trip with Do Hyung. On vacation, Bok Nyu tells Do Hyung that she knows that Detective Lee Tae Sik is associated with Do Hyung.

Sang Chul throws himself to save Bok Nyu from Do Hyung. Sang Chul's children visit Bok Nyu, who is hospitalized, but she is gone. Meanwhile, Director Hong Bun Nam and Geum Chi meet Bok Nyu's mother-in-law and request her to apologize to Bok Nyu so that she can smile again. Bok Nyu's mother-in-law allows Bok Nyu to smile again.

Na Young meets Bok Nyu and tells her that she doesn't like Bok Nyu and for her to not to be the mother to Sang Chul's children. Meanwhile, Sang Chul's children forget their mother Sun Young's birthday and wait for Bok Nyu to return. Na Young is disappointed when the children don't seem to care about her and her sister Sun Young. Na Young suddenly decides to get married, saying she will live her own life now.

Bok Nyu asks Sang Chul's children to choose between her and their mother. After hearing their honest feelings about their late mother, Bok Nyu decides to leave Sang Chul's family. Sang Chul and his children try to make Bok Nyu smile one last time before she leaves. Meanwhile, Hye Gyeol goes missing on the day Bok Nyu leaves.