The series is about an incident that takes place when the owners of the boarding house called 'Guest Summer Palace', which breaks stereotypes, and boarders with secrets gather to find Lee Seol who disappeared 13 years ago.

Eun Dan Oh is a 17-year-old high-school student from a wealthy family who suffers from a lifelong heart condition that inevitably means she will not live past her teenage years. However, when Dan Oh realizes she is experiencing long gaps in her memory as well, she comes into the unhappy inheritance of another fact in her life: she is a character in a Korean webtoon and all of her actions are predetermined by the artist who draws her.