Dr. Park Won Jang recently opened his own internal medicine clinic. His goal is to become acknowledged as a skilled physician and make a lot of money in the process. He thought that if he opened his own clinic, the money would soon roll in. Reality is a little different for Park Won Jang. His clinic receives very few patients and it is teetering on insolvency. He struggles to save his clinic. Making things worse, he also suffers from hair loss. Meanwhile, Park Won Jang is married to Sa Mo Rim. His wife trusts the advice of medical TV programs more than her husband.

Cha Young Min, a brilliant but arrogant surgeon, is involved in an accident and his spirit possesses the body of Seung Tak, a lucky and rich resident doctor. The two are complete opposites, with Young Min being cold and focused on his career, while Seung Tak, who has no interest in being a good doctor, struggles with the ghostly possession.

Sim Eun Seok is an elite judge with a prickly personality who hates juvenile offenders. After she gets assigned to a local juvenile court, she tries to balance her aversion to minor offenders with firm beliefs on justice and punishment, as she goes out of her way to break custom and administer her own ways of punishing the offenders.

In 1990s Seoul, a mysterious killer known as 'Red Cap' terrorizes the city with brutal, random attacks on women, leaving detectives powerless. To catch him, Kook Yeong Su, head of the Criminal Behavioral Analysis team, recruits former detective Song Ha Yeong, a perceptive but reserved individual, to apply criminal profiling techniques. While skeptical, homicide expert Yun Tae Gu and her team must learn to trust this new method to solve the case. As Song navigates the challenges of understanding criminals, he must also confront the emotional toll of his work.

This sweeping saga chronicles the hopes and dreams of a Korean immigrant family across four generations as they leave their homeland in an indomitable quest to survive and thrive.