After the death of her daughter, Yun-jin quits her job as a psychiatrist and hires Lisa Kim to raise her son's grades. Eun-yeong disguises herself as famous tutor, Lisa Kim, and enters Yun-jin’s home. Yun-jin searches for Kim Eun-yeong, the woman that disappeared with her daughter. And Eun-yeong looks for her sister, Jung Hyun-ju, who lent her her name and then disappeared from the hospital. They start to grow closer with one another while hiding their secrets. They slowly get closer to the truth, each in their own way, and they both learn that Jae-yeol, Yun-jin’s husband, is connected to their secrets. Realizing this, Jae-yeol uses his mistress, Se-yeon, to plot something that will destroy Yun-jin.