Every day is extraordinary for five doctors and their patients inside a hospital, where birth, death and everything in between coexist.

Cho Yeo Hwa has been a widow for 15 years. Her in-laws are the most prestigious noble family in the kingdom. During the day, she leads the life of a widow devoted entirely to her dead husband's memory and rarely ventures outside the gate of her home. At night, Yeo Hwa dons the mask of Hero, who secretly jumps over the surrounding wall to save the helpless.

Jo Dal-hwan plays Lee Ho-yeon, a salesman from a pharmaceutical company who is very people-shy.

An old man has trouble connecting with his young grandson that recently moved in. But then there are a series of mysterious attacks on the elderly, and the grandpa-grandson duo decide to investigate together and bond over the experience.