지시받은 일은 완벽하게 해내는 가정부 박복녀. 하지만 항상 모자를 깊게 눌러쓰고 웃지 않는 모습은 어딘가 수상해 보인다. 그런 그가 상철의 집에 고용된다. 아이 넷의 아버지인 상철은 오랫동안 기러기아빠로 살아왔다. 외국에서 아이들을 돌보던 아내 선영이 세상을 떠나고 아이들이 한국에 돌아오면서 상철은 집안을 꾸리는 데 도움이 필요했다. 복녀가 상철의 집에서 아이들을 돌보면서, 복녀의 비밀이 하나둘 드러나기 시작한다.
Bok Nyu is a housekeeper who does everything she is told to do. But for being a housekeeper, she seems a bit suspicious since she always wears her cap deep and never smiles. Sang Chul has four children and lived separately to provide for their education. But even though he has a wife, Sun Young, who is devoted to her family, Sang Chul has an affair. When Sun Young eventually finds out, she commits suicide. Sang Chul reunites and lives with his four children again, who have returned to Korea. He hires Bok Nyu to become the housekeeper for his family. While the mysterious Bok Nyu and the four siblings stay together, Bok Nyu's secrets start to unfold one by one.