“We are neither kids nor adults. When do we become adults then?” Min Jae and Seo Yeon are no different from ordinary 17-year-old high school students. Min Jae is silent and sensitive, yet a good student. Seo Yeon who plays the piano wished to enter an arts high school but failed. As they grow into adults, their surroundings and the reality they face get harsher. These two somehow similar but different friends get closer as they overcome their growing pains together.
In modern society, there are people who are neglected and suffering. They are often involved in unfortunate events, such as industrial accidents, and end up dying. Most of the disasters could be prevented in advance with little attention. However, some companies or public organizations tend not to prepare for potential accidents because of the high cost. That’s how industrial accidents take place. Doctor Detective is a drama where medical doctors treat the patients suffering from industrial accidents and look into the truth behind the accidents. The story of the drama starts when Joong Eun, who is an enormously talented medical doctor, gets to join an undiagnosed disease center(UDC) in the middle of experiencing difficulties in her personal life. And she starts to look into her patients' diseases caused by industrial accidents and work on revealing the truth concealed by those with power.
Stuntman Cha Dal-geon gets involved in a tragic airplane crash and ends up discovering a national corruption scandal in the process. Go Hae-ri, the oldest daughter of a deceased marine, decides to work for the National Intelligence Service as a secret ops agent in order to support her mom and younger siblings, although all she wanted to do is to become a civil servant.
Lee Jae-Sang (Rain) is a lawyer at JK Law Firm, which is one of the biggest law firms in South Korea. He is an excellent lawyer, but he only cares about winning for his benefit. One day, he has a mysterious car accident and he is drawn into a parallel world. There, Lee Jae-Sang finds himself working as a prosecutor. He is strict in carrying out the law. He is married to Ra Shi-On (Lim Ji-Yeon), who loves Lee Jae-Sang and is faithful to him. In the world where Lee Jae-Sang came from, he broke up with Ra Shi-On ten years earlier and Ra Shi-On works as a detective. Lee Jae-Sang struggles to cope with his different selves.
Eun Dong-Joo attempts to get back her stolen life. When she was 6 years-old, she was abandoned at an orphanage. She did not remember anything except her name. Despite her difficult environment, she has grown into a woman with a positive and bright personality.