Young-ran, a bottom-of-the-table woman with a criminal record and debt, is miraculously hired as the personal bodyguard of the 70-year-old chaebol chairman, Ga Sung-ho. Entering an unfamiliar mansion, she encounters the eccentric Chairman and gradually senses a suspicious atmosphere.

Chairman Ga proposes marriage to Yeong-ran. She accepts, mortgaging her life to escape her debts. To avoid his stepdaughter, Ga Sun-young, who is after his fortune, she assumes the false identity of "Boo Se-mi" and prepares to leave for the countryside, Muchang.

Young-ran, transformed into a complete opposite of her past self, disguises herself as a kindergarten teacher, Boo Se-mi, and sets foot in Muchang for the first time. As she adjusts to the unfamiliar routine, she encounters Dong-min, who happens to pass by her at the Gahoejang mansion, and a strange tension begins to flow between them.

Young-ran struggles to adjust to kindergarten life. Her first class and the theft of her kindergarten tuition deepen her conflict with the villagers. Amidst nationwide attention focused on the widow of a defunct conglomerate chairman, Young-ran hosts a welcoming party of her own to avoid the villagers' suspicions.

An unexpected guest appears at the welcoming party, and the crisis becomes an opportunity. While Yeong-ran gains the trust of the villagers, Lee Don, the headman's lawyer, faces a threat. Yeong-ran's plans are disrupted, forcing her to implement Plan B, which sparks unexpected national news coverage.

Young-ran, whose identity is revealed to single dad Dongmin, approaches his son Juwon, his weak point. Meanwhile, Young-ran is arrested by the police after an unexpected incident at kindergarten. Lee Don heads to Muchang to help her, but someone is secretly following him.

An uninvited guest with knowledge of Yeong-ran's past appears in Muchang. As tangled family histories and childhood memories resurface, Dong-min's son, Ju-won, goes missing in the village. Yeong-ran instinctively sets out to find Ju-won.

Unidentified outsiders appear in the village. Yeong Ran and Dong Min track down the suspicious figure hovering around them.

A shocking incident nearly resulted in the loss of a loved one. Determined to remain hidden, Yeong Ran heads to Seoul. At a press conference, she reveals her identity and declares a direct confrontation with Chairman Ga's stepdaughter.

A full-scale confrontation with Ga Seon Yeong begins. An unexpected figure offers Yeong Ran a deal, offering clues to Seon Yeong's weakness.Dong-min, who had come to Seoul to help Yeong-ran, who only pushed him away, finds himself in a desperate situation to save her, and the two share a bittersweet farewell.

At the edge of despair, a shocking figure appears before Yeong-ran. Holding the key to turning the situation around, Yeong-ran risks everything to save Dong-min. As Yeong-ran struggles to save her loved ones and fulfill her contract with Chairman Ga, another unexpected and shocking situation unfolds before her.

The long-awaited shareholders' meeting. Just as Seon-yeong is being appointed as the group's next CEO, Yeong-ran appears at the meeting and reveals Seon-yeong's ugly face to the world. Having fulfilled her contract with Chairman Ga and become the owner of a vast inheritance, Yeong-ran suddenly disappears from the mansion one day, filled with a strange sense of emptiness.