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.
Wie Dae-Han (Song Seung-Heon) is an ex-lawmaker and is a materialistic kind of politician. He wants to get elected as lawmaker again. One day, 18-year-old girl Da-Jung (Roh Jeong-Eui) comes to him. She tells him that he is her real father. Her mother raised four children, including Da-Jung, alone, but she died in a hit-and-run accident. Da-Jung is the only one now taking care of her 3 younger siblings. Wie Dae-Han accepts Da-Jung and her 3 younger siblings. He carries out “The Great Show” to become a lawmaker again.
Moon Suk-Goo works as a manager at Cheonrima Mart, which belongs to the Daema Group. Cheonrima Mart's future looks bleak as they don't have many customers and Moon Suk-Goo is frustrated by the store's situation. One day, Jung Bok-Dong, who was an executive at Cheonrima Group, is demoted to the CEO position at Cheonrima Mart. Manager Moon Suk-Goo begins to have hope that the store will experience a turnaround with the new CEO. In actuality, Jung Bok-Dong wants to destroy Cheonrima Mart to take revenge on the parent company for his demotion. Unexpectedly, Jung Bok-Dong's actions soon causes the store to attract customers.
Mo Seok-hee is an only child and her father runs the large company MC Group. She is beautiful, smart and rich. Mo Seok-hee appears like she is arrogant, but she struggles over her mother’s death. Her mother was killed 15 years ago. Meanwhile, Heo Yoon-do is a lawyer, but he doesn’t even have an office. He solves small problems of neighborhood residents at a restaurant. He is full of love. Miraculously, Heo Yoon-do is headhunted to join the TOP team at MC Group. The TOP team manages the affairs of the family who runs the MC Group. Their job includes covering up immoral or illegal behaviors done by the family.