The Joseon version of a Chaser about a medical practitioner who struggles to save his daughter from a terminal illness while being caught up in a plot to poison King Injong.

Royal Physician Choi Won (Lee Dong Wook),who works for the royal family, becomes involved with the plot to poision King Injong and is now a fugitive. He tries to save his daughterChoi Rang (Kim Yoo Bin), who has an incurable disease. Choi Won has raised his daughter alone since his wife passed away. Hong Da In (Song Ji Hyo) is the nurse who’s in love with him.

Meanwhile, Lee Jung Hwan (Song Jong Ho ) is the Euigeumbu detective who’s the one to capture him and he get help from bandit’s daughter, So Baek (Yoon Jin Yi) while he is a fugitive. Crown Prince Lee Ho (Im Seul Ong) is the suspicious crown prince who ends up thinking he was betrayed by the one person he trusted in the world.