The series tells the love story of Han Se Gye, an actress who must spend one week out of each month living in someone else's body, and Seo Do Jae, a man who suffers from Prosopagnosia.
A romance between a lawyer and a top actress, whose life goes downhill after becoming caught up in a scandal with a third generation chaebol. She fakes her position to become the lawyer's secretary in order to star in a famous writer's drama.
The story of an ordinary office worker named Yumi-from the point of view of the many brain cells in her head controlling her every thought, feeling, and action.